Resident Evil 0 key art

RESIDENT EVIL 0 (ZERO)

100% Completion Guide — GameCube (2002) & HD Remaster (2016)
2
Characters
11
Chapters
7
Bosses
29
Files
11
Weapons
100
Leech Charms

Game Overview

Resident Evil 0 is the prequel to the original Resident Evil: on the night of July 23, 1998, S.T.A.R.S. Bravo Team medic Rebecca Chambers and death-row ex-Marine Billy Coen fight through a stranded Umbrella train and the hidden facilities beneath the Arklay Mountains. It is a fixed-camera survival horror game with a twist — you control two characters at once via partner zapping, and there are no item boxes, so inventory is managed by dropping items on the floor.

DetailInfo
TitleResident Evil 0 / Biohazard 0
ReleaseGameCube 2002 · HD Remaster (PS3/PS4/Xbox/PC) 2016 · Switch 2019
Developer / PublisherCapcom
GenreSurvival Horror (fixed camera)
Playable charactersRebecca Chambers & Billy Coen (partner-swap system)
Main antagonistJames Marcus / the Queen Leech
Areas (in play order)Ecliptic Express → Training Facility → Laboratory (Church) → Factory → Treatment Plant
SettingJuly 23, 1998 — Arklay Mountains (the night before Resident Evil 1)
DifficultiesEasy · Normal · Hard (all selectable from the start; locked to the save file once you begin)
100% playthrough~8–10 hours (plus Leech Hunter for infinite weapons)

Read This Before You Start

Five decisions shape the whole run.

DecisionWhy it matters
Pick your difficulty for the right reasonAll three difficulties are selectable from the start, and the choice is locked to that save file once you begin. Easy has no results screen at all, so the rank rewards — the Sub-Machine Gun and Rocket Launcher — can never be earned there; ranks are awarded on Normal and Hard only, and depend on clear time alone. If you only play once, play Normal. Enemy count and every puzzle solution are identical on all three settings — only supplies and damage change.
Grab every Ecliptic Express file before the train crashesThe train files are the only missable ones of the game’s 29 files. Reading all 29 in one run earns “Fileophile” — miss a train file and the full-file run is dead.
Sweep every room before moving onThere are no item boxes — you manage space by dropping items on the floor (the map marks rooms holding dropped items). Areas become sealed off behind you, so files and items left in a finished area are gone for good. Stage heavy items where the guide tells you.
Launch Leech Hunter from a Normal or Hard clear — never EasyLeech Hunter runs at the difficulty of the cleared save you launch it from, and its infinite-ammo rewards lock to that same save and difficulty. Clear it from an Easy file and the infinite ammo only works on Easy — where no rank is ever awarded, so it can never help you unlock anything.
Budget your Ink RibbonsSaving costs an Ink Ribbon on every difficulty — this game removed item boxes, not ribbons. Expect roughly 70 on Easy, 46 on Normal, 34 on Hard across a full playthrough, and note that ranks depend on clear time alone — saving and retrying do not lower them.

Core Mechanics — Read This First

Two systems make Resident Evil 0 different from every other classic RE game. Understanding them is the whole guide.

SystemHow it works
Partner Zapping (two characters)You control one character at a time and instantly “zap” control to the other; the one you are not controlling becomes an AI Partner. You can order the partner to follow you or stay put, and set it to attack on its own or hold fire (hold fire to save shared ammo). You can switch even when the two are in different rooms — almost every puzzle is one character working a mechanism while the other stands somewhere else.
No item boxes — you DROP itemsThere are no storage chests anywhere in this game. To manage space you drop items on the floor; they stay exactly where you leave them and can be collected later (the map marks rooms that hold dropped items). Each character has 6 inventory slots; the Hunting Gun, Shotgun, Grenade Launcher and Hookshot each take 2 slots. The two hand items to each other in person when standing together.
Rebecca vs. BillyRebecca Chambers is physically weaker (dies faster) but is the only one who can mix herbs and chemicals (she carries the Mixing Set) and squeeze through narrow gaps/vents. Billy Coen takes less damage, hits harder, and is the only one who can push/move heavy objects and boost Rebecca to high places.

Warning: because there is no item box, and areas become sealed off behind you, sweep every room before moving on and stage heavy items where the guide tells you. Files and items left in a finished area are gone for good.

Story Synopsis

S.T.A.R.S. Bravo Team is sent into the Arklay Mountains to investigate cannibal murders, but their helicopter crashes. Rookie medic Rebecca Chambers boards a stopped Umbrella train, the Ecliptic Express, and finds its passengers turned into leech-covered zombies. Aboard she meets Billy Coen, a former Marine being transported for execution. Forced to work together, the two survive the train — which is hijacked and crashes into a hidden Umbrella training facility.

Beneath it they uncover the work of Umbrella co-founder Dr. James Marcus, who bred the leech creatures and was assassinated in 1988 on Spencer’s orders by his protégés Wesker and Birkin. A hooded figure conducting an orchestra of leeches turns out to be the Queen Leech — a mutant leech that consumed Marcus’s corpse, took his memories and face, and unleashed the t-Virus for revenge. After the final battle in the collapsing treatment plant, Rebecca and Billy destroy it. Rebecca reports Billy as dead to let the framed man go free, then heads for the Spencer Mansion — leading directly into the first Resident Evil.

Characters

Two survivors and the thing hunting them.

CharacterWho they are
Rebecca Chambers18-year-old S.T.A.R.S. Bravo Team medic and chemistry graduate. Weaker in a fight, but mixes herbs/chemicals and fits through small gaps. Survives into Resident Evil 1.
Billy CoenFormer U.S. Marine lieutenant, court-martialed and sentenced to death after being scapegoated for a wartime massacre. Stronger and tougher; cannot mix herbs. Innocent — Rebecca lets him walk free.
James Marcus / Queen LeechUmbrella co-founder and t-Virus pioneer, murdered in 1988. The Queen Leech absorbed his body and identity and masterminds the outbreak as his “revenge.” The final boss.

Difficulties — Easy, Normal & Hard

Resident Evil 0 has three difficulties: Easy, Normal and Hard, on both the GameCube original and the HD Remaster. All three are selectable from the start, and the difficulty is locked to that save file once you begin.

Every code and solution in this guide works on all three difficulties. Difficulty never changes a puzzle answer — the clock (8:15), the power regulator, the torch order, 385, 4863, the power grid and the chess board are identical on Easy, Normal and Hard. The only two puzzles that vary are the train brakes and the conference-room terminal code, and those are re-rolled every playthrough regardless of which difficulty you picked. The brake target is always one of five fixed numbers — 36, 42, 53, 67 or 81, so read the one your own playthrough gives you.

All 29 files exist in the same places on every difficulty too, so a 100% file run is identical whichever setting you choose.

What Actually Changes

Difficulty in this game is almost entirely about supplies, not about the map. Enemies hit harder and soak more damage as you go up, and the game hands you far less to work with — both smaller pickups and fewer pickup spots.

Supply (full playthrough)EasyNormalHard
Handgun rounds~950~635~545
Shotgun shells~133~112~91
Green Herbs~42~26~22
First-Aid Sprays~16~9~8
Ink Ribbons~70~46~34
Myth-buster: the number of enemies does not change between difficulties. The same zombies, dogs, Hunters and Eliminators stand in the same rooms on Easy and on Hard — they simply take more punishment and deal more damage. Easy is not a shorter game, it is a better-stocked one.

Saving costs an Ink Ribbon on every difficulty (this game removed item boxes, not ribbons). Only the supply changes. Your saves are colour-coded on the load screen so you can tell files apart at a glance — blue on Easy, white on Normal, red on Hard (and purple for Wesker Mode in the HD Remaster).

Which Difficulty Should You Play?

DifficultyRanksSupplies & EnemiesBest For
EasyNo rank at allRoughly double the ammo and healing of Normal, softer enemies.Learning the routes and collecting all 29 files with no pressure. No results screen means the rank rewards — Sub-Machine Gun and Rocket Launcher — can never be earned here. Easy still unlocks Leech Hunter and Wesker Mode, and an A rank in Leech Hunter still grants infinite ammo — but only for that Easy save.
NormalFull ranksThe intended balance.The default choice for a first serious run or a rank attempt. If you only play the game once, play it here.
HardFull ranksAbout 15% less handgun ammo than Normal, fewer herbs and sprays; enemies hit harder and take more.A resource-management game — same map, same puzzles, same enemy placements. It is about not wasting a single bullet, not about reflexes.
The Easy trap — read this before you touch Leech Hunter. Leech Hunter runs at the difficulty of the cleared save you launch it from, and its infinite-ammo rewards are locked to that same save and difficulty. Clear Leech Hunter from an Easy file and your infinite ammo only works on Easy — where no rank is ever awarded, so it can never help you unlock anything. Always do Leech Hunter from a Normal or Hard clear.

Beating Hard Mode

Everything below is good practice on Normal — on Hard it stops being optional.

1
Run past almost everything. Learn the step-back dodge and walk around zombies, crows, spiders and Eliminators rather than fighting them. Ammo spent on trash is ammo missing at the finale.
2
Kill Leech Zombies and Mimicry Marcus with fire, not bullets. Conventional weapons do kill them — but the body bursts apart into loose leeches that you then have to deal with separately, so you pay twice. Fire kills them cleanly and nothing crawls away. Use Molotov Cocktails (make them from empty bottles and keep making them; they are the free anti-leech resource) and save your Flame grenade rounds. Better still, sprint past them.
3
Reserve the Magnum completely for the endgame. Aim to reach the Treatment Plant with roughly 20 Magnum rounds untouched, and keep at least 2 Grenade Launcher rounds spare for the final Queen Leech phase.
4
Match the round type to the enemy. Acid rounds for Hunters and the Centurion, Flame/Incendiary for anything leech-based. The Grenade Launcher is the efficiency weapon of the game — a Hunter costs about one grenade plus a pistol shot, versus dozens of handgun rounds.
5
Keep Billy in front. Rebecca has less health and takes noticeably more punishment than Billy on every difficulty. Control Billy for fights and use Rebecca as the pack mule — with two exceptions: Rebecca throws Molotovs faster, and she is the only one who can mix herbs.
6
The knife is genuinely viable, and aim up at close range. There is no hidden damage bonus for shooting from close up — what close range buys you is the upward shotgun blast, which has a strong chance of decapitating a zombie outright and killing it in one shell. The knife is the other free weapon: the Stinger stuns after every hit, so the train boss can be killed without spending a single shell.
7
Skip the Hunting Gun, take the Shotgun. The Shotgun you find in the facility is strictly better and saves you juggling two-slot weapons. Build the Custom Handgun (Duralumin Case, code 385) as soon as you can — the improved fire rate carries the whole midgame.
8
Rotate your save slots. Ribbons are tighter on Hard but still adequate; the real danger is overwriting your only save after wasting ammo. Keep two or three slots rolling so a bad stretch is recoverable — running dry at the last boss with no earlier save is the classic Hard-mode dead end.

The Two Hard-Mode Spikes

Difficulty is a global multiplier on enemy health and damage — roughly 0.6× health on Easy and 1.2× on Hard — and no boss picks up a new attack because of it. Every fight simply lasts longer and punishes harder. Two of them are where Hard runs actually die:

Proto-Tyrant, first encounter (Factory)
The hardest fight in the game on Hard, because Rebecca faces it alone in a cramped arena with the game's most fragile character. Keep moving, fire the Magnum only when you have a clean angle, and reposition immediately — do not stand still lining up shots. A Shotgun blast to its back knocks it down and buys you free follow-ups. This is the fight players over-spend on and then arrive at the finale empty.
Queen Leech, final phase (Treatment Plant)
An attrition gauntlet where earlier waste comes due. Remember you are not trying to kill it — it is immune to gunfire. Billy only has to hold its attention while Rebecca works the shutters, so shoot to pull aggro, not to win. The on-screen timer is more generous than it looks. Aim for the tail to disorient it.
The other five bosses are comfortable if you bring the right tool: knife or Shotgun for the Stinger, the exposed white underbelly for the Centurion, and roughly five Grenade Launcher rounds to stun-lock the Infected Bat to death — the cheapest answer to that fight.

Ranks, Unlocks & the Best Order to Play

Your rank depends on clear time only. Saves, retries, healing items and even unlocked infinite-ammo weapons do not lower it — and the thresholds are the same on Normal and Hard.

RankClear timeReward
S3:30:00 or fasterInfinite Rocket Launcher (plus the Sub-Machine Gun)
A3:30:01 – 5:00:00Infinite Sub-Machine Gun
B5:00:01 – 7:00:00
C7:00:01 – 9:00:00
Dslower than 9:00:00
Easyany timeNo rank and no results screen
The efficient route through everything
1. Clear the game on Normal at your own pace (this unlocks Leech Hunter, Wesker Mode and the costumes). 2. Play Leech Hunter from that Normal save and collect all 100 charms for infinite ammo. 3. Use that infinite ammo on a Normal speed run under 3:30 for the S rank and the Rocket Launcher. 4. Take Hard on last, with the unlocked weapons available if you want them.
Speed-run essentials: fight as little as possible, skip the Hunting Gun, build the Custom Handgun early, and plan your item-drop points in advance — with no item boxes, sloppy item routing is what separates a five-hour run from a three-hour one. Pausing does not advance the timer, so you can stop and check the route.

Leech Hunter & Wesker Mode Difficulty Rules

Leech Hunter inherits its difficulty
You cannot pick a difficulty for Leech Hunter — it runs at the difficulty of the cleared save you launch it from, and its rewards stay tied to that save and difficulty. Its own rank is based on how many of the 100 charms you collect (50 blue for Billy, 50 green for Rebecca), and both characters must survive and reach the exit.
RankCharmsReward
A100Unlimited ammo for all weapons
B90–99Magnum Revolver (then found on the train)
C60–89Unlimited Hunting Gun ammo
D30–59Unlimited handgun ammo
E0–29Sub-Machine Gun ammo
Leech Hunter’s item layout is randomised across a few sets, and you can identify yours from the herbs in the main hall at the start — so if you want a particular weapon set, reset at the beginning rather than discovering it forty minutes in. Clear each room of enemies before collecting its charms, and leave the nearby rooms for last, because some rooms respawn zombies once you are near the end of the count.
Wesker Mode is locked to Normal
Wesker Mode (HD Remaster and Switch only) has no difficulty option — it always runs on Normal, and it awards no rank, so it cannot be used for an S-rank run. It is easier in practice anyway: Wesker’s Death Stare costs no ammunition at all, which removes the game’s entire resource problem, and his Shadow Dash lets you skip most fights. He can also mix herbs, which Billy cannot. Any Leech Hunter infinite ammo you have earned still applies here.

Story Walkthrough — 11 Chapters

Pick a chapter below, then use the Previous / Next buttons at the bottom of each one to move through the game.

How to read the tags. Every pickup, puzzle and split in the walkthrough carries a coloured tag, so you can skim a chapter for one kind of thing without reading all of it.
TagWhat it marks
FILE #1A readable file, numbered as the game numbers it — all 29 are needed for Fileophile
KEY ITEMOpens a door, a case or a mechanism
WEAPONA weapon you can pick up
PUZZLEA puzzle that blocks progress — the answer is in the step
PARTNER SPLITRebecca and Billy separate here — check what each is carrying first
MAPAn area map
BOSSA named fight
MISSABLEGone for this run if you walk past it
Do not finish a run without these. There is no item box in this game and no hard point of no return, but four things end a 100% attempt on the spot: the Locker Key in the basement waterfall room opposite the Battle Arena — the only key the story never hands you, and without it you lose the Duralumin Case, the Handgun Parts and the Custom Handgun; the 16 bats in the church, which is a one-time event; being picked up by the Infected Bat, which only that one boss can do; and Mimicry Marcus, whose knife-only and fire kills are two separate runs. Carry everything important to one room before the train crashes — items you never physically picked up may not survive the wreck.
CH 1Ecliptic ExpressRebecca — alone on the train

Resident Evil 0 gives you two characters with six inventory slots each, no item boxes anywhere, and no way to pass an item unless the pair are standing together. Almost every place players get stuck in this game is the same mistake: the wrong person is holding the thing. The train is also the one area you can never return to — five of the nine train files are permanently missable.

Openingthe forest & the wrecked transport
1
S.T.A.R.S. Bravo Team's helicopter goes down. Rebecca Chambers finds a wrecked prisoner-transport vehicle and the file on its escaped convict, Billy Coen. FILE #1 Player's Manual 1 is already in her inventory and FILE #2 Court Order for Transportation is handed to you during the opening. Neither can be missed.
2
She boards the stopped Ecliptic Express.
Everything on this train is a one-way trip. Once the brake sequence fires, no interior of the train is ever reachable again. Sweep every room before you touch the emergency brake.
Passenger Car 1 & 2Train 1F — 3 zombies
3
The first car is empty on this pass. In the second, three zombies get up in the entry cutscene.
Ammunition is genuinely tight here on Hard. Kill the one directly behind Rebecca and run past the rest — you will be crossing these cars several more times and they refill each time.
Officer's CarTrain 1F — the first cutscenes
4
Clear the two cabins before you touch anything here — taking the key starts the zombie repopulation behind you.
5
Take the KEY ITEM Dining Car Key from the train employee's body in the western corner. Billy Coen appears in a cutscene and walks off.
6
Edward Dewey crashes in through the window, dying, with two Cerberus behind him. Rebecca can outrun them back toward Passenger Car 2. Loot Handgun Ammo ×15 from his body.
7
Four doors lead off this car: the two cabins, the Conductor's Office (locked — Billy opens it later) and the Engine Carriage, sealed behind a Blue Keycard reader.
Cabin 202Train 1F
8
MISSABLE FILE #3 Passenger's Diary is on a suitcase underneath the table.
This is a dead-end cabin off a side corridor and it is the most-skipped room on the train. Skip it and the file is gone for the whole playthrough.
9
Ink Ribbon inside the jacket hanging by the bunk beds, and Handgun Ammo ×15 on the floor beside them (Easy and Normal only — absent on Hard).
On a replay with a B rank or better in Leech Hunter, the Magnum Revolver is on the bottom bunk here. It is the one genuinely missable weapon in the first half.
Cabin 201Train 1F — typewriter
10
This is the only save point on the entire train. It is also your staging room: with no item boxes in this game, spare items get dropped on the floor and the map screen remembers where.
11
MISSABLE FILE #4 Investigation Orders is on the lower bunk, west side — not on the desk with the typewriter, which is why people walk out without it.
12
Ink Ribbon ×3 on the typewriter table and a Green Herb by the bunks.
Dining CarTrain 1F
13
Unlock the right-hand door out of Passenger Car 1 with the Dining Car Key. Billy steps out behind you in a cutscene.
14
MISSABLE FILE #5 Notice to Supervisors is on the small table at the foot of the stairs — easy to run straight past on the way up.
15
Note the silver sliding doors right of the stairs. That is the lower end of a service lift, and it is about to become the only link between your two characters. Also note the large refrigerator — there are Empty Bottles ×3 inside it, but a zombie has to burst out first.
Restaurant CarTrain 2F — Rebecca solo
16
BOSS A Mimicry Marcus attacks in the entry cutscene.
Do not fight it. This encounter is scripted and unwinnable — Rebecca has no fire weapon. Head back toward the stairs to trigger the scene where Billy shoots it and pulls her out.
17
Afterwards you receive FILE #6 Player's Manual 2 automatically and Billy hands you Handgun Ammo ×30. Handgun Ammo ×15 is on the bench by the stairs.
18
The door to the Service Room here is jammed. It needs an Ice Pick, which Billy finds — remember that.
Dining Car RoofTrain roof — Rebecca solo
19
Climb the ladder at the end of the restaurant car and walk toward the glinting toolbox with the power cable.
20
Reaching for the cable triggers the cutscene that drops Rebecca into the sealed Service Room. This is the game's first forced split, and from here the two characters solve everything by passing items to each other.
Chapter 1 of 11
CH 2The Split & the StingerRebecca & Billy — the service lift

Rebecca is locked in a room with no exit and no typewriter; Billy is loose on the rest of the train. The dumbwaiter between the Dining Car and the Service Room is the only thing connecting them. Everything in this chapter is one long handoff.

Service RoomTrain 2F — Rebecca sealed in
1
PARTNER SPLIT Take the KEY ITEM Conductor's Key from the ledge near the door, plus a Green Herb on the south-west bench and Handgun Ammo ×15 on the north bench.
2
PUZZLE Put the Conductor's Key into the service lift in the south-west corner and send it down.
Players routinely hunt this room for a door and never notice the dumbwaiter. It is the only way forward for either character.
Dining Car → Conductor's OfficeTrain 1F — Billy solo
3
As Billy, go through the silver sliding doors right of the Dining Car stairs and take the Conductor's Key out of the lift.
The lift works both ways. Send Rebecca ink ribbons or healing if she needs them.
4
Walk Billy up the train — the passenger cars have refilled — and unlock the Conductor's Office off the Officer's Car.
5
MISSABLE FILE #7 Note from Conductor is on the floor next to the desk in the north-east corner. This is a Billy-only room and one of the five permanently missable train files.
6
Take the MAP Train Map off the wall by the door, a Green Herb and a Red Herb from the window ledge, and the KEY ITEM Briefcase from the closet in the south-east corner.
The briefcase has two ring-shaped slots. You will find the rings much later, in two places, with two different characters.
7
Press the red switch beside the exit to drop a ladder down into the Bar Lounge, then climb down.
Bar LoungeTrain 2F — Billy solo, first pass
8
You will hear scraping from the roof. That is the boss, and it drops in the moment you pick up the Ice Pick. Do not take the Ice Pick yet — go and get a real weapon first.
9
Pass straight through into the Upstairs Passenger Car.
Cabin 101Train 2F — the Hunting Gun
10
Take the WEAPON Hunting Gun from the bed in the south-west corner. It takes two of Billy's six slots and it is the answer to the boss.
11
Also here: Shotgun Ammo ×7 and Handgun Ammo ×30 on the south-east floor, a First-Aid Spray on the sink, and Ink Ribbon ×3 by the north-west desk.
12
Drop the Briefcase and anything bulky here. With a two-slot long gun equipped Billy has almost no room, and you are about to fight something.
Upstairs Passenger CarTrain 2F
13
Take the KEY ITEM Ice Pick from the small trolley by the west entrance. A Green Herb sits on the table by the antique phone (a Red Herb by the west entrance instead, on Hard).
14
Head west into the Bar Lounge. The boss lands as you enter.
Bar LoungeBOSS Stinger
15
BOSS Stinger — a giant scorpion that punches through the roof. Whoever holds the Hunting Gun fights it, which is normally Billy.
Rebecca can fight it, but she has far less health and this thing hits very hard. Billy is the right choice.
16
Weak point: the head. The rest of it is armour that eats your shells. Aim high and close.
17
Rhythm: the Hunting Gun holds two rounds — fire twice, turn and back off, reload, repeat. Roughly nine or ten shells to the head kills it. Follow with shotgun shells and the handgun if you run dry; the knife does respectable damage to the head and is a legitimate finisher.
18
Tells: an audible clatter and a plant-and-rear immediately before it lunges.
Its impale is an instant kill. And its death spasm is a heavy pincer counterattack — the moment it starts dying, back away. That final swipe kills more players than the fight does.
19
Loot the KEY ITEM Panel Opener from the roof wreckage on the west side.
The handoffDining Car service lift
20
PARTNER SPLIT Walk Billy back down to the Dining Car, put the Ice Pick into the service lift and send it up.
Billy carrying the Ice Pick around the train is the second-most common stall in the game. Rebecca is the one locked behind the jammed door — she needs it.
21
Switch to Rebecca, take the Ice Pick out of the lift and use it on the Service Room door. She comes out into the Restaurant Car, where two zombies have now appeared. Go down and reunite.
Chapter 2 of 11
CH 3The Rings & the BrakeBoth — the end of the train

Two rings, one briefcase, one keycard and a two-console brake puzzle where the second console's display is broken. This chapter is where the game teaches you, permanently, to check which character is holding the key item.

Dining Car → Freight CarTrain 1F — 2 Cerberus
1
Use the Panel Opener on the floor panel in the Dining Car to open the hatch down to the freight car.
2
Two dogs burst from their cages the instant you enter. They are fragile — one close shotgun or hunting-gun shell each.
3
Take the KEY ITEM Gold Ring from the second kennel, north-east corner, plus Gas Tank ×3 by the middle shelf, Shotgun Ammo ×7 and a First-Aid Spray on the north-west shelf.
4
Gas Tank + Empty Bottle = Molotov Cocktail. Fire is the only clean way to kill a Mimicry Marcus — bullets work, but the body bursts apart into loose leeches you then have to deal with separately. Keep making Molotovs all game; they are free.
5
Back in the Dining Car, a zombie now bursts out of the large refrigerator. Kill it and take the Empty Bottle ×3 inside.
Rear CarriageTrain 1F — PARTNER SPLIT
6
PARTNER SPLIT Both characters are required here. One stands at the lever in the south-east corner and pulls it; switch, and the other takes the KEY ITEM Hookshot off its wall mount. There is no solo version of this.
7
FILE #8 Hookshot Operator's Manual comes with it automatically.
8
Do not leave the Hookshot on the train. It has four use points across the whole game — the train roof, the church roof, and twice inside the Laboratory. Leaving it behind means a very long backtrack through the sewers later.
Officer's Car Roof → Cabin 102Train roof
9
Fire the Hookshot at the window in Passenger Car 2, climb to the roof, cross it and drop into Cabin 102. Two more zombies have spawned in each passenger car.
10
Kill the zombie inside, take the spare Knife off the floor and the KEY ITEM Jewelry Box from the north-east closet.
11
PUZZLE Examine the Jewelry Box in your inventory and rotate it. It opens and yields the KEY ITEM Silver Ring.
Carrying the box without examining it is a classic stall — people search the whole train for a ring that is already in their hands.
12
Leaving spawns leeches in the Upstairs Passenger Car. Move quickly rather than fighting.
The briefcasePUZZLE three items, one inventory
13
PUZZLE Get the Briefcase, the Gold Ring and the Silver Ring into the same character's inventory, then combine: Briefcase + Gold Ring, then + Silver Ring. It opens to reveal the KEY ITEM Blue Keycard.
14
The briefcase was staged in Cabin 101 by Billy, the gold ring came from the freight car and the silver ring from the roof route. If they are split across two characters you cannot combine them — the pair must physically meet and hand items over.
15
Use the Blue Keycard on the reader beside the Officer's Car door to open the engine carriage.
Engine Carriage & Engine CabTrain 1F
16
The two Umbrella special-forces bodies in the carriage are lying still. They only get up once the brake sequence starts — on the way in they are scenery, on the way back they are not.
17
FILE #9 Brake Operation Manual is awarded automatically on entering the cab. It tells you the brake takes three steps.
18
Take the KEY ITEM Magnetic Card from the control panel, Handgun Ammo ×15 under the cabinet by the door and another ×15 in the north-east corner.
The emergency brakePUZZLE PARTNER SPLIT — the run that ends runs
19
Sweep the entire train before you do this. Everything you have not picked up and every file you have not read is lost the moment the train crashes.
20
PUZZLE The three steps. First, swipe the Magnetic Card at the console on the rear balcony of the Rear Carriage — the very back of the train. Second, solve the number puzzle there. Third, the other character solves the same puzzle at the console in the Engine Cab, which needs no card — but its display is broken.
21
PUZZLE The number puzzle. A target number appears and you must press ten digit buttons that add up to it.
It is randomised every playthrough, so read your own number. Any ten digits that sum correctly are accepted — the easy method is nine of one digit plus a remainder. For a target of 36: 3 3 3 3 3 3 3 3 3 9. For 81: 8 8 8 8 8 8 8 8 8 9. For 67: 7 7 7 7 7 7 7 7 7 4.
22
The character you send to the back must be the one carrying the Magnetic Card. Hand it over before you split. Sending Billy to tank the zombies while Rebecca still holds the card means running the whole train twice, through cars that have completely refilled.
23
The second console is the real puzzle. Its screen is dead, so you cannot see your running total — write the target down and count your presses on paper.
24
Enemies on the run to the back: Edward Dewey (now a zombie) plus one more in Passenger Car 1, four in Passenger Car 2, one in the Officer's Car, and the two soldiers now standing up in the engine carriage.
Send Billy — he bulldozes through better. Sending Rebecca gets you an extra cutscene with Edward, which is the only reason to do it.
25
Both consoles solved, the train derails into the Umbrella Executive Training School. The Ecliptic Express is now closed forever.
Chapter 3 of 11
CH 4Training Facility — Ground FloorBoth — arrival and the west wing

The facility is the opposite of the train: nothing here is permanently missable. A four-level elevator you unlock much later lets you come back for anything you skipped. That makes it the right place to be thorough rather than efficient.

Train Passage & Sewer PassageTraining Facility B1 — 4 zombies
1
Four zombies climb out of the fire around the wrecked train. Run for the far door.
2
Note the elevator down here. Late in the game it becomes the game's safety net — four buttons that take you back to the Training Facility, Factory B1, Factory B4 and the Treatment Plant. Anything you skip in the next few hours can be retrieved through it.
3
Follow the sewer passage and climb the ladder up into the Main Hall.
Main HallTraining Facility 1F/2F — typewriter
4
A two-storey safe room with no enemies and a typewriter on the desk by the foot of the staircase.
This is your item box. RE0 has none — you drop spares on the floor and the map screen remembers where they are. Make this desk your dumping ground for the entire facility.
5
Ink Ribbon ×3 and Handgun Ammo ×15 on the typewriter desk (Easy and Hard both give ×30 here), plus a Green Herb and Red Herb on the floor beside it.
6
PUZZLE Note the statue holding a set of scales beneath a painting. That is the way into the basement and it needs two figurines you have not found yet.
Dining Room & Boiler RoomTraining Facility 1F
7
Two zombies in the dining room and Handgun Ammo ×15 on the east table. A corpse in the north-west corner reanimates much later, during the basement rescue.
8
The boiler room behind it holds Green Herb ×2, a Red Herb and a Blue Herb behind the boiler.
Blue herbs cure poison — the giant spiders in the basement are what they are for.
9
The kitchen off the dining room is locked behind the Fire Key, which is two bosses away. Come back for it — the Lighter Fluid inside is mandatory.
Storage RoomTraining Facility 1F — 2 zombies
10
Take the WEAPON Shotgun, propped against the shelves in the south-west corner. This is your workhorse for the whole facility.
11
Take the KEY ITEM Black Statue from the ornamental table by the north windows, and Gas Tank ×6 from the south-west floor.
12
Stage the Black Statue back at the Main Hall desk. You cannot use it until you have found a second figurine and two sets of wings.
West Wing Corridor & BathroomTraining Facility 1F
13
A Mimicry Marcus is waiting in each of these rooms — leeches fused into a humanoid. When its health drops low it self-destructs, and that explosion is the real damage. Fire prevents the detonation entirely: one Molotov or a Napalm grenade kills it cleanly. Killing it with bullets scatters loose leeches you then have to stamp out.
14
The bathroom holds Empty Bottle ×3 in the middle of the floor, a Green Herb and Gas Tank ×6 by the north-west cubicles.
Projection RoomTraining Facility 1F — 2 zombies
15
Handgun Ammo ×30 on the north-west table (×15 on Hard).
16
The projector here is the machine that turns two microfilms into the MO Disk. You will be back once you have both — one is upstairs in the main library, the other in the private study.
Living RoomTraining Facility 2F — 4 crows
17
FILE #10 Notice to All Staff is on the table beside the armchair in the middle of the room.
Read it. It announces two Security Level 5 meetings and states the entry code is 8:15. That is the clock puzzle's only clue.
18
Take the KEY ITEM Crank Handle from the small cupboard by the south-east windows.
Four crows smash through the windows the instant you take it. Do not waste ammunition — walk out.
Private Study RoomTraining Facility 2F — 4 zombies
19
The densest ordinary zombie room in the building. FILE #13 A Verse of Poetry sits on the western edge of the central table — the hierarchy-and-balance riddle that hints at the scales.
20
Take KEY ITEM Microfilm B from the east mantelpiece, plus Shotgun Ammo ×7 in the north-east corner (absent on Hard).
Lecture RoomTraining Facility 2F — typewriter
21
Second save point. FILE #11 Regulations for Trainees is on one of the many student desks in the centre. Ink Ribbon ×3 and Shotgun Ammo ×7 by the typewriter table.
22
The podium terminal in front of the desks is where the MO Disk goes, and those student desks are the puzzle. Note also the knight-statue door in the corner — there are three of them in the building and the MO Disk opens all three at once.
Chapter 4 of 11
CH 5The Clock & the CenturionBoth — the upper floors

Three co-operative puzzles back to back — a lift that needs one person cranking, a cage that needs one person winching, and a boss that grabs Rebecca and does not let go until Billy kills it.

Art Corridor & Main LibraryTraining Facility 2F — PARTNER SPLIT
1
Take the MAP Training Facility Map from the reading desk in the middle of the library and KEY ITEM Microfilm A from the north-west bench. Ink Ribbon ×3 on the computer desks.
2
PARTNER SPLIT The library lift. Stand Rebecca on the platform in the south-east corner, switch to Billy, and use the Crank Handle on the wall mechanism to raise her to the clock room.
You cannot crank with the character standing on the platform. This trips people constantly.
3
Note the unlit candles here. Lighting them opens the Small Library, and that needs a working lighter — which needs the kitchen, which needs the Fire Key. It is a chain, and it starts with the boss below.
Clock RoomTraining Facility 3F — 2 Plague Crawlers
4
Two Plague Crawlers drop from the ceiling.
Stand on the stairs and pick them off with the handgun — from up there they cannot reach you.
5
Handgun Ammo ×15 on the north-east table, Shotgun Ammo ×7 by the lift, and a First-Aid Spray near the clock on Easy.
6
PUZZLE The large clock is missing its hand. You need the Iron Needle, which is behind the Fire Key door. Note it and move on.
Fountain AreaTraining Facility 3F — 5 crows
7
Ignore the crows. A Green Herb and a Red Herb lie by the fountain.
Art RoomTraining Facility 2F — 2 Plague Crawlers
8
Do this room before you touch the Fire Key. The WEAPON Grenade Launcher is on the west couch, and it turns the boss you are about to fight from a slog into a formality.
9
Take the KEY ITEM White Statue from the small round table by the easel, and Shotgun Ammo ×7 from inside the fireplace — genuinely easy to walk past.
10
The water-design door out of this room stays locked for a long time. It needs a key from the very bottom of the basement.
Large HallTraining Facility 2F/3F — PARTNER SPLIT and BOSS
11
PARTNER SPLIT Send Rebecca down the ladder into the drained pool, switch to Billy and work the winch to raise the cage, then switch back and take the KEY ITEM Fire Key from underneath it.
12
BOSS Centurion — a giant centipede, triggered the instant the key comes out.
13
You fight it as Billy, and you have no choice. The Centurion seizes Rebecca immediately and chips away at her health for the entire fight. There is no instant-kill move here — the way this boss kills you is by taking too long. Speed is the survival strategy.
14
Weak point: the pale underbelly, exposed only when it stops and rears the front of its body up. Its armoured back absorbs everything, so do not shoot while it is moving — wait for the rear, fire, back off, repeat.
15
With the Grenade Launcher it takes roughly four grenades. With the shotgun, budget fifteen to twenty shells. Heal both characters afterwards — Rebecca will be hurt even if Billy never got touched.
KitchenTraining Facility 1F — Fire Key door
16
Take the KEY ITEM Lighter Fluid from the table and Empty Bottle ×3 from the shelf underneath.
17
PUZZLE Combine Lighter Fluid with Billy's empty Lighter — he carries it as default equipment — to make the working KEY ITEM Lighter.
The Lighter is Billy's, in practice. Both the library candles and the entire animal-statue puzzle in the basement require Billy standing at the object with the Lighter in his inventory. Hand it to Rebecca and you will walk it back.
Assistant Director's OfficeTraining Facility 2F — Fire Key door
18
FILE #12 Assistant Director's Diary on the desk opposite the fireplace.
19
PUZZLE The Iron Needle. It is stuck in the antlers of the moose head above the fireplace. To reach it you must turn on the light switch in the north-west corner and push the table in front of the fireplace to climb on.
Two separate environmental steps, neither signposted. This is where people decide the needle must be somewhere else.
20
Handgun Ammo ×15 on the west desk (×30 on both Easy and Hard) and Shotgun Ammo ×7 in the south-west corner.
Clock RoomPUZZLE 8:15
21
PUZZLE Use the Iron Needle on the clock to fit the missing hand, then set the time to 8:15: the long minute hand to the Roman numeral III and the short hour hand to VIII. In practice: turn the minute hand right three times, then the hour hand left four times.
22
The clue is the Notice to All Staff file from the living room, which states the entry code outright. The answer is fixed on every difficulty.
23
The time-locked doors in the facility open.
Chapter 5 of 11
CH 6MO Disk, Chess & the ScalesBoth — opening the basement

Four puzzles that gate each other: two microfilms make a disk, the disk opens three doors, one of those doors hides a chessboard, and the chessboard plus a candle-lit library produce the two figurines that open the floor of the main hall.

Projection RoomPUZZLE the microfilms
1
PUZZLE Take Microfilm A (main library, north-west bench) and Microfilm B (private study mantelpiece) to the projector. Insert both.
2
You receive the KEY ITEM MO Disk and FILE #14 Microfilm Image automatically.
The Microfilm Image is not flavour text — it is your decoder sheet. It maps a 4×4 grid of student desks to the characters 0–9 and A–F.
Lecture RoomPUZZLE PARTNER SPLIT — the terminal
3
PUZZLE Insert the MO Disk into the podium. The terminal boots and displays a two-character code.
4
The code is randomised every playthrough. Any guide that prints a specific answer is publishing its own roll. What is fixed is the desk layout — read your code, look it up on the Microfilm Image, and find the two matching desks.
5
PARTNER SPLIT Station one character at each of the two matching desks and press both switches in quick succession. There is a timer, so position both before you start.
6
All three knight-statue doors unlock at once: the facility entrance, the private corridor and the observatory tower.
Marcus' OfficeTraining Facility 2F — PUZZLE the chessboard
7
Through the private corridor. Napalm Grenades ×6 on the cabinet by the globe, Ink Ribbon ×3 on the circular table, Handgun Ammo ×15 on the east cabinet.
8
PUZZLE The chessboard. The clue is on the desk — examine it and you get a small reference board showing the layout the floor pieces have to match.
9
As Billy, push the white King: toward the exit door until it reaches the next-to-last square → move to its right and shove it one square left → get behind it and push it toward the other pieces → onto its final square, directly below the white Rook.
Misplaced it? Leave the room and come back — the pieces reset to their starting positions. There is no way to lock yourself out.
10
The desk's hidden compartment opens: KEY ITEM Book of Evil and FILE #16 Marcus' Diary 1.
11
PUZZLE Examine the Book of Evil in your inventory to extract the KEY ITEM Black Wing.
Carrying the book without examining it is the same trap as the jewelry box on the train.
Medicine RoomTraining Facility 2F — 2 zombies
12
FILE #15 First Investigation Unit Notes is on one of the beds — a frequently missed file.
13
MISSABLE Take the KEY ITEM Green Chemical standing in the north-east corner.
This is needed hours later, in the Laboratory, and only Rebecca can use it — she owns the Mixing Set. Leave it here and you will be walking all the way back for it.
14
First-Aid Spray on the medicine cabinet and Blue Herb ×2 on the lower shelf.
Main Library → Small LibraryPUZZLE the candles
15
PUZZLE As Billy, light the candles in the main library with the Lighter. The Small Library opens.
16
Inside: Grenades ×6 on the south-west bookshelf and the KEY ITEM Book of Good, in a compartment on the pillar behind the moveable bookcase in the upper area.
17
PUZZLE Examine the Book of Good to extract the KEY ITEM Angel Wings.
Main HallPUZZLE the scales of good and evil
18
PUZZLE Black Statue + Black Wing = Statue of Evil. White Statue + Angel Wings = Statue of Good. Place both on the scales held by the large statue.
19
Consolidate first. The black statue came from the ground-floor storage room, the white one from the second-floor art room, and the two wings from two different books in two different rooms. If any of the four are in the wrong character's inventory you cannot combine them.
20
The clue is A Verse of Poetry from the private study — the moon bowing to the earth, the earth to the sun, and a door that no hands can open. Hierarchy and balance.
21
The painting beneath the scales slides aside, revealing the staircase down into the facility basement.
Chapter 6 of 11
CH 7Facility BasementBoth — the regulator and the rescue

The basement is where the game separates you properly. Rebecca falls through a floor and Billy has to walk half the facility alone to reach her — through the Eliminators, which are the first enemy in this game that can genuinely kill you from full health.

Basement EntranceFacility Basement B1 — 3 giant spiders
1
Three spiders crawl the walls and ceiling and spit venom.
Kill them fast rather than dodging — poison is a slow drain and the blue herbs are back up in the boiler room. Fire is very effective.
Observation RoomFacility Basement B1 — typewriter
2
Take the MAP Training Facility Basement Map off the wall beside the typewriter.
3
FILE #17 Correctional Institute Inmates List on the south-west table, with Handgun Ammo ×30 on the same table. Ink Ribbon ×3 by the typewriter, plus a Green Herb and Blue Herb on the floor.
4
Make this your second staging room. Everything in the basement routes back through here.
Monitor RoomFacility Basement B1 — 2 zombies
5
One of the two zombies is playing dead on the floor. It is a scripted ambush — expect it.
6
Handgun Ammo 3×15 on the middle table, Shotgun Ammo ×7 in the south-east corner and Gas Tank ×6 by the north-west locker.
Torture Rooms A & BFacility Basement B1 — PARTNER SPLIT PUZZLE
7
PARTNER SPLIT In Torture Room A, Billy boosts Rebecca up through the open ceiling grate to reach the regulator side. From this moment Rebecca is on her own.
8
FILE #18 About the Power Regulator is on the floor in the south-east corner of Torture Room B.
This is the clue file and it is unusually direct: set the indicator to 70, and check that everything is connected to the chain.
9
PUZZLE The power regulator. The wall panel has five switches. Set them UP, UP, DOWN, UP, UP — first two up, middle one down, last two up. The needle lands on 70.
The answer is fixed on every difficulty and never re-rolls.
10
Restoring the power collapses the floor and Rebecca falls into the basement below. You now control Billy alone until you reach her. There is no timer — she is safe until you arrive, so take the fight seriously rather than sprinting.
The rescueBilly solo — the Eliminators
11
Eliminators now populate the route: one in the observation room, two in Torture Room A, three in Torture Room B. They soak an unusual amount of ammunition — roughly two close shotgun shells each — and their jumping back-bite locks into a chain of follow-up bites that can kill you outright from a healthy bar.
12
Fight them from a doorway. They charge in a line, so standing at the entrance funnels them one at a time instead of letting them surround you.
13
Route: Main Hall → Dining Room (the corpse in the north-west corner gets up now) → Boiler Room (B2)Storage Room (B2).
14
The B2 boiler room has Green Herb ×2, a Red Herb and a Blue Herb behind the boiler, and a shortcut straight up to the ground-floor dining room.
Storage RoomFacility Basement B2 — typewriter
15
Rebecca is here. Save, take the Ink Ribbon ×3 on the south-west boxes (×1 on Hard) and reunite.
Statue RoomFacility Basement B2 — 3 Eliminators, PUZZLE
16
Handgun Ammo ×5 in the south-west corner of the passage toward the storage room — note the unusual quantity.
17
PUZZLE The animal statues. As Billy, stand at each statue, open his inventory and use the Lighter. The order is the food chain, weakest to strongest: deer → wolf → horse → the big cat → snake → eagle.
18
Rebecca cannot do this — the Lighter has to be in Billy's inventory when he stands at each statue. And note the fourth statue: guides variously call it a tiger, a cougar or a lion. It is the same statue, in the same position — go by the hierarchy, not the name.
19
There is no file anywhere in the game that spells this order out. The only in-game guidance is the carvings on the statues themselves, read as a predator hierarchy. It is the least-clued puzzle in RE0.
20
The gate on the south side opens into the cavernous area and the B3 complex below.
Bunk Rooms A & BFacility Basement B2
21
MISSABLE The KEY ITEM Unity Tablet is in the fireplace in Bunk Room A, with Empty Bottle ×3 on the south-east desk.
It is one of three tablets you need for the observatory. Sitting in a fireplace, in an optional side room, it is very easy to walk past.
22
FILE #19 Management Trainee's Diary is on the table in the middle of Bunk Room B, guarded by two zombies.
Cavernous Area & Waterfall RoomFacility Basement B2/B3
23
Two giant spiders in each half of the cavern. In the waterfall room, two Plague Crawlers are feeding on the west side — shotgun or grenade them as you enter.
24
MISSABLE Take the KEY ITEM Locker Key from the wooden box.
Miss this and you lose the Custom Handgun — the only weapon upgrade in the game.
Training RoomFacility Basement B3 — PARTNER SPLIT and 2 Hunters
25
Upstairs control room: Handgun Ammo 2×15 on the south-east bench, Shotgun Ammo ×7 on the north bench, and Magnum Ammo in the north-east cupboard (×8 on Easy, ×1 on Normal and Hard).
26
Open the north-west locker with the Locker Key for the KEY ITEM Duralumin Case.
27
PUZZLE The Duralumin Case. Examine it in your inventory — the code 385 is printed on the cover. There is no separate document; the case is its own clue. Enter it for the KEY ITEM Handgun Parts.
28
MISSABLE Combine the Handgun Parts with a handgun to build the WEAPON Custom Handgun.
There is only one set of parts in the game, so only one character gets the upgrade. The improved fire rate carries the entire midgame — give it to whoever you fight with.
29
PARTNER SPLIT The arena. Rebecca goes up to the control panel; Billy goes into the cage below. Rebecca presses the left button so Billy can reach the Acid Grenades ×6 in the south-east corner, then the centre button to unlock the grate, and Billy presses the red button in the north-west corner to start the fight.
30
Two Hunters. This is the game's introduction to them and they are the fastest thing you have met. They decapitate outright when your health is low, so heal to full before you press the red button. Grenade Launcher loaded with Acid Grenades is the intended answer.
31
Take the KEY ITEM Water Key from the floor of the north-west hole the Hunter came out of.
The game labels both this and the Fire Key simply Facility Key, which is why walkthroughs appear to contradict each other. This is the water-etched one, and it opens the door out of the art room.
Chapter 7 of 11
CH 8The Piano Bar & the TabletsBoth — leaving the facility

The Water Key opens a west wing full of small key items, and one of them — the Battery — is behind the single most notorious moment in the game. Collect three tablets and the building itself moves.

Narrow Corridor ATraining Facility 2F — Water Key door from the art room
1
A Mimicry Marcus patrols here, and killing it with bullets leaves loose leeches behind.
Use a Molotov or a Napalm grenade. Fire kills it outright and nothing crawls away.
Broadcast Room & Maintenance RoomTraining Facility 2F
2
Take the KEY ITEM Vise Handle from the east shelves in the broadcast room (one Mimicry Marcus standing on that side).
3
PUZZLE In the maintenance room, use the Vise Handle on the vise in the south-east corner to release the KEY ITEM Obedience Tablet. Shotgun Ammo ×7 on the north-east shelves.
Old LaboratoryTraining Facility 2F
4
First-Aid Spray on the south-west metal table, Handgun Ammo ×15 on the east table (×30 on both Easy and Hard), and a Green Herb, Red Herb and Empty Bottle ×3 inside the small glass room to the north.
5
Entering this room is what spawns the Mimicry Marcus back in Narrow Corridor B. Clear the corridor on the way out, not on the way in.
Piano BarTraining Facility 2F — PARTNER SPLIT the Battery
6
PUZZLE Billy must play the piano — he is the pianist, Rebecca cannot do it. The wall opens into a secret wine room.
7
Inside: Magnum Ammo ×8 on a barrel, Empty Bottle ×3 on the floor, and the KEY ITEM Battery embedded in a slot on the far wall.
8
The trap. Taking the Battery out of its slot closes the wine room again. If Billy is the one inside holding it, you are stuck until you put it back. Leave Billy outside, send Rebecca in for the Battery, and have Billy play the piano a second time to reopen the wall and let her out.
9
Check inventory space before you go in. If Billy is carrying a two-slot long gun and the Handgun Parts, there may be no room to shuffle things at the critical moment.
Training Facility EntranceTraining Facility 1F — knight door, PUZZLE
10
PUZZLE Outside the main entrance is a dead lift. The character carrying the Battery places it in the slot in the wall.
It has to be the carrier standing there — the same species of mistake as the magnetic card at the brakes.
11
The lift descends to reveal a large wooden crate. Push the crate across to the pillar, climb it, and take the KEY ITEM Discipline Tablet from the top.
Outside BalconyTraining Facility 2F — 4 zombies
12
Green Herb ×2 in the northern offshoot.
This balcony repopulates hard as the game goes on — Eliminators after the basement, and Hunters once you reach the factory. It is a corridor, not a place to fight.
Observatory TowerTraining Facility 3F — PUZZLE the three tablets
13
PUZZLE Bring all three tablets: Unity (bunk room fireplace, B2), Obedience (maintenance room vise, 2F) and Discipline (entrance pillar, 1F).
14
All three must be on the same character. Consolidate before you climb, or you will be switching back and forth at the panel.
15
Cross the balcony, take the ladder to the upper level of the dome, and open your inventory at the control panel with the three indentations. The tablets slot themselves.
16
Handgun Ammo ×30 on the boxes by the upper entrance (Easy and Normal only).
17
Cutscene: the entire observatory tower lowers from the third floor to the ground, sinking partway into the water and opening a route to the outside area and the church beyond.
18
Before you leave, take stock. Nothing here is lost — the four-level elevator will bring you back — but the return trip is long. Make sure you have the Hookshot, the Green Chemical from the medicine room, the Grenade Launcher and the Custom Handgun with you.
Chapter 8 of 11
CH 9The Church & the LaboratoryBoth — the deepest split

The most split-heavy stretch in the game. Rebecca works the upper laboratory floor alone while Billy works the lower one, and the two of them pass chemicals and charms to each other through a dumbwaiter. Only Rebecca can mix anything — she owns the Mixing Set.

Outside AreaLaboratory 1F — PUZZLE the pressure pad
1
PUZZLE The church door. Take the right-hand fork into the small building and have one character stand on the floor tile inside it. That holds the church door open; walk the other character in, then recall your partner.
2
Shotgun Ammo ×7 inside the small building on Easy, and herbs near the elevator to the north-west.
Church Back RoomLaboratory 1F — typewriter
3
Go right into the side room first. The boss trigger is tied to leaving it, so this typewriter is your prep room — and there is no other save point until deep in the laboratory.
4
Ink Ribbon ×3 on the shelves by the north door, Shotgun Ammo ×7 on the east floor, and Napalm Grenades ×6 also on the east floor — Easy and Normal only, absent on Hard.
5
Give Billy the shotgun and heal both characters before you step back out.
ChurchBOSS Infected Bat
6
BOSS A giant bat smashes through the ceiling as you re-enter, with a continuous stream of small bats behind it. Fight it as Billy — Rebecca gets grabbed too easily.
7
Use the shotgun. The grenade launcher's arc is awkward against something hugging the ceiling. Roughly eight to twelve close blasts puts it down.
8
Stand at or near the altar. The camera there gives you the widest view of the nave, which is the whole fight. And thin the small bats with the handgun if they are wrecking your auto-aim — you do not have to clear them, only stop them from stealing your lock-on.
9
Its attacks are a knockdown swoop and a grab that damages and drops you. Nothing here is an instant kill, but repeated grabs will finish Rebecca quickly.
Church RoofLaboratory 2F — PUZZLE the Hookshot
10
PUZZLE The bat tore a hole in the roof. Stand underneath it and use the Hookshot from your inventory.
Send Rebecca up — it saves backtracking later, because she is the one who works the upper laboratory.
11
If you left the Hookshot on the train, this is where the game stops. You have to walk back through the observatory, the balconies, the main hall and down the sewer hatch to the wrecked train to fetch it.
12
Cross the roof, climb down into the fenced yard behind the church, take the Red Herb on the ground, flip the wall switch to power the outdoor elevator, and unlock the gate from the inside so your partner can join you.
13
Ride the elevator down to Laboratory B2.
Reference RoomLaboratory B2 — typewriter and PARTNER SPLIT
14
The laboratory's main save room and staging point. Ink Ribbon on the desk by the item transport (×6 Easy, ×3 Normal, ×1 Hard).
15
MISSABLE FILE #20 Marcus' Diary 2 is on a table at the end of a bookcase on the west side.
It is in the save room, which is exactly why people miss it — they walk in, save and walk out.
16
PARTNER SPLIT As Rebecca, use the Hookshot on the ceiling here to reach the Leech Room on B1. Billy stays down in the library.
Send Rebecca, not Billy. Everything upstairs needs the Mixing Set, and only Rebecca has it. Send Billy and she has to fetch a Green Chemical from the training facility all over again.
Leech Room & CorridorLaboratory B1 — Rebecca solo
17
One Mimicry Marcus here — fire, as always.
18
Take the MAP Lab Map off the wall by the north-west door and FILE #23 Laboratory Manager's Diary from the chair by the south-west computer desk.
19
Take the KEY ITEM Leech Capsule from the cabinet next to the large glass capsules in the north-east, plus Gas Tank ×6 and Empty Bottle ×3.
20
PUZZLE In the corridor, press the wall button. It retracts a wall down on B2 for Billy, opening his route onward. This is the first of several cross-floor favours.
Leech Laboratory & Operating RoomLaboratory B1 — Rebecca solo
21
MISSABLE FILE #22 Leech Growth Records is on the east table.
This is the clue for the cable-car dial. The growth figures read 4, 8, 6, 3 — that is the combination.
22
Take the KEY ITEM Red Chemical from the south-west corner, by the gas experiment chamber's control panel. The chamber itself is full of poison gas and holds a key you cannot reach yet.
23
In the operating room: FILE #24 Investigator's Report on the floor by the operating table, a second KEY ITEM Green Chemical against the south-west wall, and a First-Aid Spray on the north shelf. Two zombies wander, and a third gets up later.
24
PUZZLE Rebecca's chemistry, part one. Red Chemical + Green Chemical = Stripping Agent. Then Stripping Agent + Leech Capsule = KEY ITEM Blue Leech Charm.
25
Send the Blue Leech Charm down the item transport to Billy.
Marcus's Study & Private RoomLaboratory B2 — Billy
26
Billy uses the Blue Leech Charm on the blue-indentation door off the elevator passage.
27
Take the KEY ITEM Input Regulator Coil from the west bookcase.
28
MISSABLE FILE #21 Old Photograph is behind the coil on that same bookcase — you have to search the shelf again after taking the coil.
This is the most-missed file in the laboratory. Nothing tells you there is a second thing there.
29
Through into Marcus's private room: two zombies, one slumped on the floor that rises shortly after you enter, and the KEY ITEM Green Leech Charm in the hand of the statue.
30
Send the Green Leech Charm up the lift to Rebecca.
Morgue & the gas chamberLaboratory B1 — Rebecca
31
Rebecca uses the Green Leech Charm on the indentation door in the operating room. Two zombies inside — one playing dead, one crawling.
32
Take the KEY ITEM Sterilizing Agent from the south floor, plus Handgun Ammo 2×15 on the south-west stretcher.
33
PUZZLE Back in the leech laboratory, use the Sterilizing Agent on the control panel outside the gas chamber to vent the poison. Go in and take the KEY ITEM Breeding Room Key. Two more zombies wake as the door opens.
Breeding RoomLaboratory B1 — 2 Hunters
34
Two Hunters. Load Acid Grenades before you open the door and heal to full — they decapitate at low health.
35
MISSABLE FILE #25 B.O.W. Report is on the floor among the breeding cages in the north-east corner.
It is behind the Hunter fight, which is why almost everyone leaves without it.
36
Take the KEY ITEM Dial from the floor of the left-hand cage, south-east.
Elevator PassagePUZZLE the combination door — 4863
37
PUZZLE Use the Dial on the locked white door and enter 4 – 8 – 6 – 3, rotating until the red arrow points at each digit and confirming each one.
38
The clue is the Leech Growth Records file. The code is fixed — it does not re-roll, and it is the same on every difficulty.
39
Behind the retracted wall in this passage: a Red Chemical in the north-east corner, herbs by the west door, and one more Mimicry Marcus waiting.
Machine RoomsLaboratory B1/B2 — PUZZLE the cable car
40
In Machine Room 1F, pull the switch on the southern wall. It drops the KEY ITEM Output Regulator Coil on the ground by the cable-car doors and lowers a ladder.
41
Send Rebecca up with the Hookshot to Machine Room 2F, which has a typewriter, Ink Ribbon, Empty Bottle ×3, Gas Tank ×3 and Shotgun Ammo ×7 in the control room. Save.
42
PUZZLE Insert both coilsInput (Marcus's study) and Output (machine room floor) — into the control room panel to power the cable car.
43
Then it goes wrong on purpose. Heading for the cable car, a Mimicry Marcus attacks and separates Billy. Kill it with fire. Leeches then infest the 2F control room and knock the Output Coil onto the floor — go back, clear them, pick the coil up and re-seat it. Only then does the cable car run.
Cable CarLaboratory B2 — the Magnum
44
MISSABLE Take the WEAPON Magnum from the dead body sitting near the front of the carriagebefore you operate the controls.
This is the only Magnum a normal playthrough ever gets, and you are about to need it for a boss fight that Rebecca has to take alone.
45
Consolidate before you ride. Give Rebecca the Magnum, ink ribbons and healing — the game is about to make her fight solo, and it does not warn you.
46
Operate the controls. The cable car carries you to the Factory.
Chapter 9 of 11
CH 10The FactoryRebecca alone — the Proto-Tyrant

Short, and the hardest single fight in the game. The factory hands Rebecca a boss with no partner to draw its attention, in a sealed room, with the lowest health bar of the two characters. It also gives you the elevator that reopens the entire game behind you.

Platform & Turntable YardFactory 1F
1
Green Herb ×2 on the ground in the north-east corner by the cable-car doors, and Handgun Ammo ×30 on a barrel by the north-west door on Easy.
Turntable Monitor RoomFactory B1 — PARTNER SPLIT 2 Hunters
2
PARTNER SPLIT Use the small lift in the upper-right corner of the turntable yard to send Rebecca down alone along the narrow balcony.
3
Take the KEY ITEM Up Key from the floor by the wall of monitors in the south-east.
Different guides call this the Up Key, the Factory Key or the C. Panel Key. It is one object.
4
Two Hunters spawn after you take it, as you turn to leave — and Rebecca is alone. Have the Grenade Launcher with acid rounds, or the Magnum, in her hands before you send her down here.
Turntable Control RoomFactory 1F — typewriter
5
Save. Take the MAP Factory Map from the north wall, a First-Aid Spray from the north-west wall cabinet, Handgun Ammo ×30 on the north-east consoles, Ink Ribbon on the desk, and Grenades ×6 in the south-east corner (Easy and Normal only).
6
PUZZLE Use the Up Key on the computer on the left-hand wall. The turntable car is raised and the large elevator is summoned. Then push the switch to lower the turntable and ride down.
Turntable PlatformFactory B4 — BOSS Proto-Tyrant
7
As you approach, Enrico Marini stumbles out of the western elevator and is shot dead in a cutscene.
8
MISSABLE Take the KEY ITEM Elevator Key from the ground beside that western elevator.
Drop a herb if your inventory is full — do not leave this platform without it.
9
Use the Elevator Key on the eastern elevator.
10
BOSS Proto-Tyrant, first encounter.
The security shutters slam shut and Rebecca fights it completely alone. Billy is not present. She has the lowest health in the game, no partner to pull aggro and nowhere to run. This is the hardest fight in Resident Evil 0 and it arrives with no warning.
11
Use the Magnum you took off the cable car — roughly five to seven rounds. Acid grenades work too, at around eight. Anything weaker is a losing race.
12
Its two attacks are a charging lunge and a heavy overhead swipe that knocks Rebecca down for very large damage. There is no instant-kill move — what kills people is the knockdown loop, because two connections in a row is most of her health.
13
Side-step at the last moment, then fire while it recovers. Do not stand still lining up a perfect shot; it closes distance faster than you expect.
The four-level elevatorFactory B1/B4 — the safety net
14
This elevator reopens the whole game. Its four buttons go to Lv1 the training facility tunnel, Lv2 Factory B1, Lv3 Factory B4 and Lv4 the Treatment Plant. Anything you skipped since the train crash — the Custom Handgun, a file, the Hookshot — is retrievable from here.
15
MISSABLE Take the Lv2 detour now. The Maintenance Shaft holds Magnum Ammo ×8 by the elevator in the east corner, Handgun Ammo ×15 on a south-east oil drum and herbs by the west door.
Magnum rounds are the scarcest resource in the endgame and this cache sits behind an optional button press. One Hunter is waiting when the lift doors open.
16
Take Lv4 down to the Treatment Plant when you are done.
Chapter 10 of 11
CH 11Treatment Plant & the Queen LeechBoth — the finale

The longest area in the game, and Rebecca starts it alone again. Everything here funnels into one chemistry chain and one final fight in which you can only control Billy — and losing Rebecca loses the game.

Control RoomTreatment Plant B5 — typewriter and PUZZLE
1
Save. Ink Ribbon ×3 and Handgun Ammo ×30 on the desk, Gas Tank ×6 by the north door.
2
PUZZLE The power distribution board. A wall of red lights that has to go fully green in three button presses. Press: the button directly below the top-left button, then the button directly above the bottom-left button, then the button up-and-left of the bottom-right button.
3
The board is fixed — it never re-rolls and it is identical on every difficulty. Describing the presses relative to the corners is deliberate: guides that count absolute rows disagree with each other because they index the grid differently.
Air Regulator Room, 'L' Corridor & Rec RoomTreatment Plant B6 — Rebecca solo
4
Three zombies in the air regulator room, with Empty Bottle ×3 by the west door and herbs opposite it. A Mimicry Marcus patrols the corridor beyond.
5
Take the MAP Treatment Plant Map from the east wall of the rec room, plus Empty Bottle ×3 on the south-east table.
6
Note the handle-less door in the corridor, with a square socket. It leads to the generator room and you will come back with the Handle.
Maintenance Area & Water PoolTreatment Plant B7 — Lurkers
7
A Lurker — a giant toad — may leap out of the water as you pass. Its tongue grabs and swallows you, and that is an instant kill. With Rebecca alone here, this is the most dangerous corridor in the area.
8
Once the pair are reunited, a swallowed character is recoverable: switch immediately to the other character and shoot the Lurker. The swallowed one cannot act and will die if you hesitate.
9
Note the KEY ITEM Keycard on the ledge in front of the forklift. You cannot reach it yet — the forklift is dead and needs a battery you have not built.
10
In the water pool: Shotgun Ammo ×7 in the western equipment locker, and the KEY ITEM Handle visible on a platform across the water. That needs both characters, so leave it for now.
Stairway & Dumping AreaTreatment Plant B7/B8 — reunion
11
The leeches on the stairway respawn every single time you enter. Do not fight them — sprint through. You will use this stairway many times.
12
Rebecca finds Billy in the dumping area and you have both characters again.
Water PoolPUZZLE PARTNER SPLIT — the crates
13
PUZZLE Rebecca works the console, Billy pushes the crates. The floor is a rotating grid.
14
As Billy, climb the wooden crates and push the metal box right, against the wall → Rebecca presses Rot.R → Billy pushes the metal box up to the top wall through the open gate → Billy pushes the wooden crate nearest the ladder across to the far end → Rebecca presses Rot.R again → Billy pushes the middle wooden crate right, then along to join the others → Rebecca uses Fill/Drain to flood the lower floor.
15
The correctly placed crates form a bridge. Cross and take the KEY ITEM Handle.
16
You cannot break this puzzle. Misplace a crate and simply leave the room and come back — every crate resets to its starting position.
Generator RoomTreatment Plant B6/B5 — 6 zombies
17
Use the Handle on the square-socket door. Six zombies inside — five wandering and one playing dead in the south-east corner.
Fight from the left corner by the entrance so they funnel toward you instead of surrounding you.
18
Handgun Ammo ×30 in the south-east corner.
19
MISSABLE Climb the ladder to the upper walkway. FILE #26 Investigator's Report 2 is on a dead body in the south-west corner — the walkway is easy to skip entirely.
20
MISSABLE Take the KEY ITEM Red Chemical from the south-east wall up here.
Give it to Rebecca. It is one of the three ingredients for the battery, and she is the only one who can mix anything.
21
Green Herb ×2 on the north side of the walkway.
B6 Walkway & LodgingsTreatment Plant B6 — typewriter
22
Two Hunters lurk on the walkway. Equip the Grenade Launcher or Magnum before you open the door — this ambush catches people badly.
23
The lodgings are a genuine safe room. Save. FILE #28 About Battery Fluid is on the south-east bunk — the clue file for the chemistry that follows.
24
MISSABLE Napalm Grenades ×6 are underneath the south-west bunk bed. Very easy to miss and free heavy ammunition. Also here: Ink Ribbon, Handgun Ammo ×30, a First-Aid Spray on the north-east table and herbs on the east side.
Cargo Control RoomTreatment Plant B7 — 3 zombies
25
MISSABLE FILE #27 Treatment Plant Manager's Diary is on the floor in the south-west corner. Shotgun Ammo ×7 on a box in the same corner.
26
The gondola terminal in here is dead until you bring it a motherboard — and examining it is a global trigger that repopulates the maintenance shaft, the turntable platform, the rec room and the B6 walkway with fresh zombies. Do your backtracking before you touch it.
Water Treatment RoomTreatment Plant B9 — BOSS Proto-Tyrant
27
Take both characters down the lift. Load the Grenade Launcher and the Magnum and heal both.
28
BOSS Proto-Tyrant, second encounter — it comes out of the pool as you pass.
This one is much easier than the factory fight, because you have two characters. Control Billy and physically put him between the Proto-Tyrant and Rebecca — he soaks the aggro while she fires freely from behind. Roughly five or six Magnum rounds plus a few grenades ends it.
29
Afterwards, press the green wall button on the walkway to lower the ladder, and take the KEY ITEM Motherboard from the ground below the broken circuit box in the north-east corner.
The gondolaPARTNER SPLIT — Rebecca alone again
30
PUZZLE Back at the cargo control room, stand the motherboard carrier at the dead control panel and use the Motherboard. The gondola activates.
31
PARTNER SPLIT Only Rebecca fits in the transport chest. She rides down to the floodgate control room alone; Billy has to take the long way round through the dam on B9.
32
Rebecca: Acid Grenades ×6 by the destroyed stairs in the south-west corner of the floodgate room, then turn the lever on the control panel to lower the water levels.
33
Rebecca, laboratory (B8): take the KEY ITEM Blue Chemical by the north door and the KEY ITEM Industrial Water from the north-west desk. Acid Grenades ×6 under the north-east desks on Easy and Normal. One Plague Crawler.
34
Billy, the dam route (B9): Green Herb ×2 at the end of the east walkway, one Lurker in the water, and in the engine room two zombies with Shotgun Ammo ×7 and Handgun Ammo. Note the card-reader door there — that is where the Keycard goes.
Laboratory Cryo RoomTreatment Plant B9 — reunion, PARTNER SPLIT and PUZZLE
35
The pair reunite here.
36
PARTNER SPLIT The KEY ITEM Empty Battery sits on a high shelf beside the cryogenic tubes. Billy has to lift Rebecca up to it.
37
Two Plague Crawlers burst out of the cryo tubes the instant you take the battery. Have the shotgun ready before you reach for it.
38
PUZZLE Rebecca's chemistry, part two — the battery chain.
Blue Chemical + Red Chemical = Sulfuric Acid
Sulfuric Acid + Industrial Water = Battery Fluid
Battery Fluid + Empty Battery = KEY ITEM Hi-Power Battery
39
It is Blue + Red, not Red + Green. Red + Green is the Stripping Agent, which belongs to the leech capsule back in the laboratory and has nothing to do with the battery. The giveaway: there is no Green Chemical anywhere in the Treatment Plant. Only Rebecca can perform any of these combinations.
Maintenance AreaPUZZLE PARTNER SPLIT — the forklift
40
PUZZLE Backtrack to B7. Approach the forklift from the right, open your inventory and use the Hi-Power Battery.
41
PARTNER SPLIT Rebecca climbs onto the crate on the lift platform and Billy drives the forklift, raising her to the ledge. She takes the KEY ITEM Keycard.
Fenced Area & IncineratorTreatment Plant B9 — BOSS Queen Leech
42
Use the Keycard on the reader on the western engine-room doors. Magnum Ammo ×8 on the floor in the north-west corner of the passage — take it, you are about to need it.
43
Magnum Ammo ×8 also in the south-east corner of the incinerator itself, on Easy and Normal.
44
BOSS Queen Leech, first encounter — the cutscene as you enter is Marcus shedding the human disguise. Both characters are present.
45
Play as Rebecca so you instinctively keep your distance, and let Billy anchor the damage. The arena is large — use all of it.
46
It has no resistance to any weapon type, so the Magnum is simply the fastest — around eight to ten rounds. Its acid spit is survivable;
its grab is what kills you. It drains a huge chunk of health in one go. Never be at close range, and heal immediately if it lands.
47
On death it drops the KEY ITEM Shaft Key (L) and KEY ITEM Shaft Key (R).
The twin shaft keysPUZZLE PARTNER SPLIT
48
PUZZLE Split the pair — one character at the left panel with Shaft Key (L), the other at the right panel with Shaft Key (R) — and use them together to open the double doors into the storage room.
49
This is also a spawn trigger: a Hunter appears in the dumping area, three zombies in the B8 laboratory and one on the B7 walkway. Do not plan a leisurely backtrack afterwards.
StorageTreatment Plant B9 — typewriter, final prep
50
Save. This room is a full resupply: Ink Ribbon ×3 and Handgun Ammo ×30 on the north-east table, First-Aid Spray ×2, Shotgun Ammo ×7, Grenades ×6 and Napalm Grenades ×6 on the south-east shelves, plus herbs.
51
The most important loadout decision in the game. In the final phase you can only control Billy. Give Billy the Magnum, the Grenade Launcher with ten or more rounds, the shotgun and a First-Aid Spray. Give Rebecca healing and something serviceable — but nothing you will need, because you will not be able to use it.
52
Heal both to full, save, and activate the cargo elevator.
Cargo RoomTreatment Plant 1F — BOSS the finale
53
FILE #29 Gate Operation Manual is handed to you automatically when you go to open the shutters. It is the last file in the game.
54
BOSS Queen Leech, phase one. Both characters are controllable and it plays exactly like the incinerator fight.
Do not burn your Magnum rounds here. Chip it down with the shotgun and handgun and use the stairs for height — everything good goes into phase two.
55
BOSS Phase two — Billy only.
Rebecca acts on her own and you cannot control her. She runs to four valves to open the ceiling shutters. If the Queen catches her, she dies and you lose. Your entire job is defensive.
56
The tactic: every time Rebecca breaks for a valve, the Queen turns to chase her. At that exact moment, hit it hard with the Magnum or the Grenade Launcher to pull the aggro back onto Billy. Once it is coming at you, stop attacking and just survive until she reaches the next valve. Then repeat.
57
You do not need to learn the valve positions — Rebecca finds them herself. And the on-screen timer is not a real threat: play the aggro game properly and it ends long before the clock does. Panicking and chasing damage is what gets Rebecca killed.
58
With all four valves turned, the roof shutter opens and sunlight floods the room. The Queen Leech is photosensitive — that is the real weakness, and it is why you saved the Magnum. Finish it in the sunlight.
59
Its body falls down the elevator shaft and burns. Birkin has already armed the self-destruct; Rebecca and Billy escape, and the game ends at dawn with Billy walking away and Rebecca reporting him dead.
Saving your cleared file unlocks Leech Hunter and, in the HD Remaster, Wesker Mode. Rank rewards depend on clear time only — see the Difficulties and Unlockables tabs.
Chapter 11 of 11

Puzzles & Codes — Every Solution

Only two puzzles are randomized: the train brakes and the conference-room terminal code. They are re-rolled every playthrough, so read your own numbers — the brake target is always one of 36, 42, 53, 67 or 81. Every other code below is fixed and identical on Easy, Normal and Hard.
PuzzleAreaAnswer / CodeHow to Solve
Train BrakesEcliptic ExpressRandomizedTwo panels (rear balcony + driver’s cabin), activated with the Magnetic Card. Each shows a target number; press ten digits (1–9) that add up to it. Fastest way: press as many 9s as fit, then fill the remainder — e.g. target 67 = seven 9s (63) then 2+1+1. The cabin screen is broken, so track that one yourself.
ClockTraining Facility 3F8:15Mount the Iron Needle, then turn the minute hand to III (15) and the hour hand to VIII (8) and confirm. Opens the two clock-marked doors. The hint is in Notice to All Staff.
Conference DesksTraining Facility 2FRandomizedProject Microfilm A + B to get the desk chart, insert the MO Disk in the terminal to read a two-character code, then set both characters to solo, stand one at each coded desk and press together. Opens the armored doors.
Chess BoardMarcus’s Office 2FMatch the reference boardMove only the piece that is out of place so the big board matches the small board on the desk. A wrong move releases poison gas; leaving the room resets it. Reward: Book of Evil → Black Wing.
Statues of Good & EvilMain HallBoth statues on the scalesAngel Wings + White Statue = Statue of Good and Black Wing + Black Statue = Statue of Evil. Place both on the scales — the basement staircase opens under the painting.
Power RegulatorFacility BasementUP · UP · DOWN · UP · UPSets the needle to 70 and restores power. The target is stated in the About the Power Regulator file.
Animal TorchesFacility BasementDeer → Wolf → Horse → Tiger → Snake → EagleLight the animal statues weakest to strongest with the fuelled Lighter (Lighter Fluid comes from the kitchen behind the Fire Key door). Opens the blocked passage.
PianoFacility Bar 2FBilly plays it — twiceBilly plays to slide the wall open; send Rebecca in for the Battery (plus Magnum ammo and empty bottles), then Billy plays again to reopen the door so she can get out.
Duralumin CaseFacility Basement B3385Inside the locker opened with the Locker Key. Examine the case to read the code, enter 385Handgun Parts → combine with a handgun for the Custom Handgun.
Three TabletsObservatory 3FUnity + Obedience + DisciplineUnity from the bunk-room fireplace, Obedience from the vise (needs the Vice Handle), Discipline from the front-yard column (Battery-powered lift + Billy pushes a crate). Slot all three to lower the tower to the Laboratory.
Cable-Car DialLaboratory4863Take the Dial to the Machine Room lock and enter 4-8-6-3. The hint is in the Leech Growth Records file.
Factory TurntableFactoryUP Key — raise, cross, lowerUse the UP Key at the control panel to raise the turntable, cross it, then lower it to reach the level below and the Elevator Key.
Power GridTreatment PlantRow 6 / Col 2 → Row 2 / Col 2 → Row 6 / Col 3Three presses light every point (each button also lights the points two spaces away). Restores power and opens the way down.
Crate & Water BridgeTreatment PlantBilly pushes — Rebecca rotates & floodsBilly shifts the wooden and steel crates while Rebecca turns the machine between pushes; finally Rebecca runs the fill device so the wooden crates float into a bridge. Cross for the Handle.

Combinations & Chemical Recipes

Everything you build in the game, in the order you unlock it. Only Rebecca can mix chemicals and herbs — she carries the Mixing Set.

You GetRecipeWhat It’s For
Lighter (fuelled)Empty Lighter + Lighter FluidLights the animal-statue torches
Custom HandgunHandgun + Handgun PartsStronger sidearm — parts from the Duralumin Case (385)
Molotov CocktailEmpty Bottle + GasolineThe free anti-leech weapon — use these instead of Flame rounds
Stripping AgentGreen Chemical + Red ChemicalDissolves the Leech Capsule
Blue Leech CharmStripping Agent + Leech CapsuleOpens the blue leech-marked door in the Laboratory
Sulfuric AcidBlue Chemical + Red ChemicalFirst step of the battery chain
Battery FluidSulfuric Acid + Industrial WaterFills the Empty Battery
Hi-Power BatteryBattery Fluid + Empty BatteryPowers the Forklift → exposes the Keycard

Key Items — What Opens What

Key ItemWhere / Use
Mixing SetRebecca’s starting kit — combines chemicals and herbs
HookshotTrain balcony — grapples across gaps (roofs, church roof, leech room)
Gold / Silver Ring → BriefcaseTrain — both rings open the Briefcase for the Blue Keycard
Blue Keycard / Magnetic CardTrain — driver’s cabin access; brake sequence
Crank / Vice Handle, Handle, Panel OpenerOperate lifts, vises, vents and machinery
Facility / Fire / Water KeyTraining-facility & basement doors
Angel Wings + Black Wing / StatuesBuild the two statues to open the basement
Leech Capsule → Leech CharmLab — opens leech-marked doors
Input / Output Reg. CoilLab — power the cable car
Battery / Empty → Hi-Power BatteryFacility lift; treatment-plant forklift
MotherboardTreatment Plant — powers the gondola
Shaft Key (L) & (R)Finale — the two locks before the Queen Leech

Enemies — Threat & Counter

Fire is the recurring answer to anything leech-based — kill those with Molotovs or Flame rounds, or they burst back into a swarm. Everything else is a judgement call between the ammo it costs and the damage it deals.

EnemyThreatHow to Handle It
ZombieLow — run pastInfected passengers and staff. Learn the step-back dodge and walk around them; a close-range Shotgun blast aimed up can decapitate for an instant kill when you must fight.
Cerberus (Dog)LowFast infected Dobermans that leap. Cheap to kill — a few handgun rounds each. Shoot them mid-jump or keep spacing so they cannot pin you.
CrowLow — run pastSwarm and peck at the head. They cost more ammo than they are worth; just keep moving.
Leech / Leech SwarmLow — use fireIndividual leeches that reproduce and merge. Burn them or stomp them; the danger is only in letting them pile up.
Mimicry MarcusHigh — never shoot itLeeches merged into a humanoid. Bullets kill it, but the body breaks apart into loose leeches — fire kills it cleanly. Use a Molotov, or simply sprint past. It also only takes damage before and after its transformation animation.
Plague CrawlerMediumA large mutated centipede that closes fast and hits with little warning. Control Billy and shoot down at it; flame weapons work well. (Not the Centurion boss.)
Giant SpiderMedium — skipWall-crawling spiders that spit venom. Shoot them while they are still on the ceiling, or walk past. Carry a Blue Herb or Green Chemical for the poison.
EliminatorMedium — avoid in the openInfected apes: extremely fast, bounce off walls and attack in groups. Fight them one at a time in a doorway if forced, otherwise outrun them.
HunterHigh — kill only if forcedReptilian B.O.W. that leaps and can decapitate a wounded character. The efficient answer is one Acid grenade plus a pistol shot; killing one with handgun rounds alone wastes a huge amount of ammo.
Lurker (Giant Frog)Very High — do not gambleIts tongue can swallow you for a near-instant kill. This is the one enemy where conserving ammo is the wrong instinct — use your strongest weapon immediately, or zig-zag out of range.
Infected BatsLowSwarm around the church and lab. The Shotgun’s spread clears several at once; you can ignore the small ones entirely during the boss fight.

Bosses at a Glance

BossAreaWho FightsBest WeaponKey Point
1. StingerEcliptic ExpressBillyHunting Gun / knifeBack to the doorway, aim down at the head. Drops the Panel Opener.
2. CenturionFacility BasementBilly aloneShotgun / Grenade LauncherShoot the white underbelly when it rears up. Rebecca is captured — be quick.
3. Infected BatChurchBillyGrenade LauncherAim up; about five rounds stun-lock it to death. Ignore the small bats.
4. Proto-TyrantFactoryRebecca aloneMagnumThe hardest fight on Hard. Keep moving, fire on clean angles only. Driven off, not killed.
5. Proto-TyrantTreatment PlantBothMagnum + Grenade LauncherBilly tanks in front. Killed for good this time.
6. Queen LeechTreatment PlantBothMagnumStay mobile, dodge the acid spit and the grab. Heal immediately after a grab.
7. Queen Leech (final)Treatment PlantBothSunlight — not gunsImmune to gunfire. Billy shoots only to hold its attention while Rebecca opens the shutters.

Bosses — Full Strategy

BOSS 1 Stinger (Giant Scorpion) — Train[+]
Where
Ecliptic Express bar/dining car, early. Billy fights (Rebecca is separated).
Kill it
Put your back to the rear wall to limit its pincer reach, aim slightly down at the exposed head, and keep firing the Hunting Gun while healing. It has low HP — just avoid its flailing death throes.
BOSS 2 Centurion (Giant Centipede) — Facility Basement[+]
Where
Breeding-pool / cage room. Billy fights alone — Rebecca is captured and her health drains on a timer.
Kill it
This is a race: free Rebecca fast. Circle-strafe the arena, target the belly when it rears up, and unload the Shotgun / Grenade Launcher. If you’re slow, Rebecca dies.
BOSS 3 Infected Bat — Church[+]
Where
The chapel/church, between the Training Facility and the Laboratory. Fight as Billy (higher defense).
Kill it
Stand near the altar with your back to a wall to avoid the lift-and-drop grab. Snap-aim up and fire the Shotgun — its spread hits the boss and the summoned bats together. The Grenade Launcher is hard to land on a fast aerial target.
BOSS 4 Proto-Tyrant (First Encounter) — Factory[+]
Where
Right after the cable car. Rebecca fights alone with the Magnum from the cart.
Kill it
Kite it — keep moving, don’t over-aim (it closes fast), and fire the Magnum (~6 shots) when you have a clean angle. Heal immediately after its knock-down swipes; never let it corner you.
BOSS 5 Proto-Tyrant (Second Encounter) — Treatment Plant[+]
Where
Lower treatment room. Both characters.
Kill it
Tag-team: position one character behind it while both fire — with two shooters (Magnum / Grenade Launcher / Shotgun) it goes down quickly. Last time you see it.
BOSS 6 Queen Leech — Phase 1[+]
Where
Treatment-plant battle room. Both characters; extra Magnum ammo is stocked here.
Kill it
Sidestep its arcing acid spit and melee lunges, pour in Magnum rounds, and heal as needed to force it into its final form.
BOSS 7 Queen Leech — Final Phase[+]
Where
Upper arena at dawn. It cannot be killed by gunfire alone.
Kill it
Set Rebecca to Idle/Solo and control Billy. Keep shooting the Queen Leech (Magnum) to draw its lunges away while Rebecca opens the shutters. When sunlight floods in, its UV weakness ends the fight. The lab self-destructs.

Weapons & Ammo

WeaponAmmoWhere / Notes
Combat KnifeBilly starts with one; a second is in cabin 202. Last resort.
Handgun (x2)Handgun BulletsRebecca & Billy start with one each. Billy’s is slightly stronger.
Custom HandgunHandgun BulletsBase handgun + Handgun Parts (Duralumin Case, code 385). Faster follow-up shots.
Hunting GunShotgun ShellsTrain cabin 101. Break-action, holds 2 — the weaker shotgun. (Infinite at Leech Hunter C-rank.)
ShotgunShotgun ShellsFacility statue room. Holds 7; angle up for grouped headshots. The crowd-control workhorse.
Grenade LauncherGrenade / Flame / Acid roundsPast the centipede area. Flame rounds shred leech enemies; Acid for certain bosses.
MagnumMagnum RoundsBody in the lab cable-car cart. Strongest standard gun — save it for the Tyrants and Queen Leech.
Molotov CocktailthrownCraft from an empty Glass Bottle + Gasoline. Great vs. leeches.
Sub-Machine Gun% ammoUnlockable — A rank (clear under 5:00). Added to Billy on later runs.
Rocket LauncherinfiniteUnlockable — S rank (clear under 3:30). One-hit kills but slows you down.
Magnum RevolverMagnum RoundsLeech Hunter B-rank reward — then hidden on the train.
Resident Evil 0 has no minigun and no separate ‘Samurai Edge’ unlock — the starting handgun is merely modeled on it.

Files — “Fileophile”

Read all 29 files in a single playthrough for the completion reward. Files cannot be collected after you leave an area, so read each as you pass it.

The only files you can permanently miss are on the Ecliptic Express — once the train crashes you can never go back. Grab every train file (the five marked MISSABLE above) before you solve the brakes. Every later area allows enough backtracking that its files are safe.
#FileLocation
1Player's Manual 1Ecliptic Express — automatic (opening tutorial)
2Court Order for Transportation MISSABLEEcliptic Express — wrecked transport at the start
3Passenger's Diary MISSABLEEcliptic Express — passenger cabin
4Investigation Orders MISSABLEEcliptic Express — save room
5Notice to Supervisors MISSABLEEcliptic Express — dining car
6Player's Manual 2Ecliptic Express — automatic
7Note from Conductor MISSABLEEcliptic Express — conductor's room floor
8Hookshot Operator's ManualEcliptic Express — automatic (with the Hookshot)
9Brake Operation ManualEcliptic Express — automatic (driver's cabin)
10Notice to All StaffTraining Facility 2F — crank-handle room (hints 8:15)
11Regulations for TraineesTraining Facility — conference room, 2F
12Assistant Director's DiaryTraining Facility — Iron Needle room
13A Verse of PoetryTraining Facility — Microfilm B room
14Microfilm ImageTraining Facility — automatic (after projecting the microfilms)
15First Investigation Unit NotesTraining Facility — infirmary bed (easily missed)
16Marcus' Diary 1Training Facility — automatic (after the chess puzzle)
17Correctional Institute Inmates ListTraining Facility basement — save room
18About the Power RegulatorTraining Facility basement — power-regulator room
19Management Trainee's DiaryTraining Facility basement — past the animal-statue gate
20Marcus' Diary 2Laboratory — library (by the typewriter)
21Old PhotographLaboratory — Marcus's Study, behind the Input Reg. Coil on the west bookcase
22Leech Growth RecordsLaboratory — tank room (cable-car dial hint 4863)
23Laboratory Manager's DiaryLaboratory — leech-zombie room
24Investigator's ReportLaboratory — tank room
25B.O.W. ReportLaboratory — Hunter room floor (easily missed)
26Investigator's Report 2Treatment Plant — balcony level
27Treatment Plant Manager's DiaryTreatment Plant — motherboard / gondola room
28About Battery FluidTreatment Plant — beds/typewriter room
29Gate Operation ManualTreatment Plant — automatic (final boss room)

Unlockables & Extras

UnlockableHow to Get ItDetails
Leech HunterClear the game once (any difficulty)Bonus minigame. Collect 100 Leech Charms (50 blue for Billy, 50 green for Rebecca) and get both characters out of the front door. Launch it from a Normal or Hard save — the rewards lock to that save’s difficulty.
Infinite ammo (all weapons)Leech Hunter — 100 charmsRank A in the minigame. The lower bands give: 90–99 Magnum Revolver, 60–89 infinite Hunting Gun, 30–59 infinite handgun, 0–29 Sub-Machine Gun ammo.
Infinite Rocket LauncherS rank — clear under 3:30Appears in Rebecca’s inventory on the next new game. One-hit kills, but it slows you down.
Infinite Sub-Machine GunA rank — clear under 5:00Appears in Billy’s inventory on the next new game. An S rank grants this as well.
Wesker ModeClear the game onceHD Remaster and Switch only — it does not exist on GameCube. Wesker replaces Billy with a Shadow Dash and an ammo-free Death Stare, and he can mix herbs. Locked to Normal and awards no rank.
Team Wesker costumeFinish Wesker ModeUnlocks Rebecca’s Team Wesker outfit for the main campaign.
Closet Key / costumesClear on Normal or HardThe key appears in cabin 101 on a replay and opens the alternate outfits for Rebecca and Billy. The HD Remaster adds further default and paid DLC costumes.
Ranks are awarded on Normal and Hard only and depend on clear time alone — saving, retrying and using unlocked infinite-ammo weapons do not lower them. The efficient route is: clear Normal → Leech Hunter on that same save for infinite ammo → use it for a sub-3:30 run. Full detail in the Difficulties tab.

100% Checklist

Finish the campaign (Ecliptic Express → Facility → Lab → Factory → Treatment Plant).
Read all 29 files in one run for “Fileophile” (grab every Ecliptic Express file before the train crashes — those are the only missable ones).
Build the Custom Handgun (Duralumin Case, code 385).
Clear Leech Hunter with 100 charms for infinite ammo on all weapons — launch it from a Normal or Hard save, never Easy.
Clear on Normal/Hard in under 5:00 (A rank) for the Sub-Machine Gun.
Clear in under 3:30 (S rank) for the infinite Rocket Launcher.
HD Remaster: clear the game, then finish Wesker Mode (unlocks Rebecca’s Team Wesker costume).
Unlock the alternate costumes.

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