Resident Evil Gaiden: Recompiled

Resident Evil Gaiden: Recompiled (PC / Native)

A native static recompilation of Resident Evil Gaiden (Game Boy Color, 2001) for modern PC and Android platforms, built in C/C++ with hardware-accelerated SDL2, OpenGLES 3, and Dear ImGui.

Running directly on native hardware without CPU emulation overhead, this project modernizes the classic maritime survival horror experience with Configurable Dash / Sprint, True Widescreen, Dynamic 2D Flashlight Lighting, Atmospheric Horror Shaders, Touch Controls, a Verified Cheats Engine, and an HD Texture Pack Engine.

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Note on defaults: the game boots looking like an unmodified Game Boy Color - native 10:9 aspect, native GBC colours, no shaders, no flashlight, no HD pack. Every enhancement below is opt-in or configurable from the in-game menu (F10), and your choices are saved to config.ini.

Highlights & Features

1. Configurable Dash / Sprint System (Windows & Android)

• Fixes Sluggish Overworld Exploration: Addresses Resident Evil Gaiden's notoriously slow walking speed by adding an optional sprint system.
• Context-Sensitive B-Button Dash (Enabled by default): Holding Game Boy B while moving with the D-Pad automatically sprints without opening the inventory. Tapping B while stationary opens the inventory screen as normal.
• Dedicated Dash Bindings:
  • Keyboard: Hold Left Shift or Right Shift.
  • Gamepad: Hold R1 (Right Shoulder) or L1 (Left Shoulder).
  • Android Touch Screen: Dedicated on-screen >> sprint button in Electric Blue positioned above the B button.
• Configurable Modes & Speeds:
  • 0 = Disabled (1x Walk Only)
  • 1 = Hold Button to Run (Default - 200% / 2x Speed)
  • 2 = Always Run (Whenever Moving)
  • Speed slider adjustable from 125% to 250% in the new Gameplay settings tab.
• Combat & Menu Safety: Automatically deactivates in battle (ROM Bank 13/14) and menus/inventory (gb_state_is_ui_screen), preserving 100% original combat meter timing, hit detection, and CD audio pitch.

2. True Widescreen & Ultrawide Viewports (16:9 & 21:9)

• Eliminates Camera Crunch: Expands the horizontal exploration viewport from 20 tiles (160px) to 32 tiles (256px - 16:9) and 42 tiles (336px - 21:9) directly in C.
• Corridor Sightlines: Look deep down the narrow corridors of the luxury ocean liner Starlight to spot approaching zombies before bumping into them.
• Aspect Ratio Modes: Toggle seamlessly between Native 10:9 (160×144), True Widescreen 16:9 (256×144), and True Ultrawide 21:9 (336×144) at runtime.

3. Dynamic 2D Flashlight Lighting & 2D Horror Atmosphere

• Real-Time Directional Flashlight: Barry's flashlight casts a real-time directional beam of light down dark ship hallways.
• Directional Tracking: Light cone automatically rotates to match Barry's movement (Up, Down, Left, Right) based on input.
• Ambient Darkness & Attenuation: Unlit areas are shrouded in darkness with smooth radial distance gradients and cosine angular falloff.
• Halogen Bulb Jitter: Realistic high-frequency subtle bulb flicker and warm halogen color temperature.

4. Atmospheric Retro Survival Horror Shaders

• Vignette Lighting: Radial corner shadow falloff for an authentic claustrophobic survival horror atmosphere.
• Cinematic Film Grain: Temporal animated procedural noise simulating 90s classic survival horror film grain.
• CRT Scanlines & Phosphor Mask: Alternating horizontal scanline darkening and subpixel RGB shadowmask.
• 5 Horror Color Grading Profiles:
  • Native GBC Colors
  • Cold Biohazard Blue (cool teal cast with rich shadow contrast)
  • Bleach Bypass Gritty (high-contrast desaturated look)
  • Sepia Retro (aged vintage horror tone)
  • Silent Monochrome (classic black-and-white noir mode)

5. HD Texture Pack & Modding Engine (hd_pack/)

The bundled hd_pack/ is AI slop. It is a quick proof of concept to show the engine works, nothing more - machine-generated placeholder art that does not match the game's style and was never meant to ship as a finished look. Please replace it. See Making Your Own Asset Packs below. If you make something good, open a PR or an issue and it can be linked from here.

• Native PNG Decoder: Embedded stb_image for zero-dependency high-speed image loading.
• Host-Resolution Compositing: High-definition assets render at full native monitor resolution (1080p / 4K):
  • hd_pack/backgrounds/: HD 16:9 pre-rendered battle backgrounds (e.g. Starlight Corridor).
  • hd_pack/monsters/: HD battle monster and zombie sprites.
  • hd_pack/portraits/: HD character dialogue portraits (Barry Burton, Leon S. Kennedy, Lucia).
• Hot-Reloading: Edit or swap PNG assets and click "Reload HD Textures" in the in-game menu without restarting the game.

6. Replacement Soundtrack (music_pack/)

• Bring Your Own Music: Drop .ogg or .wav files into music_pack/ to replace the in-game soundtrack.
• Follows the Game: Tracks are matched to the game's own music ids, so the right music plays in the right place. Any id you have not supplied keeps the original music.
• Sound Effects Preserved: Game Boy music and SFX share the same four channels, so the emulated audio is ducked rather than muted while your music plays - gunshots, doors and menu blips still come through.
• No music is bundled. Like the ROM, the files are yours to supply.

7. Built-in Cheats & GameShark Code Engine

• Hardware-Verified Built-in Cheats: Re-anchored to real Game Boy Color disassembly memory addresses:
  • Infinite Health: Barry (100 HP), Leon (100 HP), Lucia (120 HP), with poison status and counters cleared automatically.
  • Infinite Ammo: Max ammo (99) for all 5 weapon ammo pools (Handgun, Shotgun, Grenade Launcher, Assault Rifle, Rocket Launcher).
  • Unlock All Weapons: Grants knife, handgun, shotgun, grenade launcher, and rocket launcher in inventory bitmasks.
  • Infinite Items: Sets max First Aid Sprays, Green/Red Herbs, and Kevlar Armor in inventory.
  • Freeze Combat Reticle / Always Perfect Hit: Centers and locks combat reticle to target, overrides hit outcome to 0 (perfect hit), and guarantees critical hits.
  • One-Hit Kill in Battle: Direct damage calculation hooks at pc_44e3, loc_0d_49c2, and loc_0d_5f8e + RAM clamping, defeating any zombie, creature, or the Tyrant in 1 hit.
• Banked GameShark Code Support: Full support for Game Boy Color GameShark codes (01xx standard and 9Bxx WRAM banked codes) with whitespace/hyphen tolerance.

8. Multi-Slot Savestate Manager

• 10 Dedicated Savestate Slots: Save and load instantly via the in-game overlay menu or shortcut keys (F5 Save, F8 Load, F6/F7 Slot change).
• Automatic battery-backed SRAM persistence for native in-game typewriter save points.

9. Modern Controller, Keyboard & Mobile Touch Controls

• Full support for XInput (Xbox), PlayStation (DualShock / DualSense), Retroid Pocket, and generic USB gamepads.
• Android Virtual Touch Gamepad: On-screen D-Pad, action buttons, dedicated >> sprint button, quick settings button, and controller show/hide toggle.
• Portrait & Landscape Adaptive Layouts with in-game orientation locking.
• Live in-game rebinding interface with analog stick support and rumble-ready architecture.

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Platform Availability & Roadmap

• Windows (x86_64): Fully supported with static CRT, embedded icon, and release archive (Release v0.4.1).
• Android (ARM64-v8a): Fully supported with touch gamepad, Retroid Pocket optimization, and legal ROM onboarding (Release v0.4.1).
• Linux (x86_64 / ARM64): Native SDL2 + Vulkan build in active preparation.

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Making Your Own Asset Packs

Both asset packs are plain folders of ordinary files. Nothing is compiled in, nothing is packed into an archive - drop files in, restart or hot-reload, done. No tooling required.

About the bundled hd_pack/: it is AI slop. It exists purely to prove the engine works. The art is machine-generated placeholder junk that does not match the game's aesthetic, and it should not be taken as the intended look. If you have any pixel-art ability at all you will do better. Please replace it - and if you make something good, open a PR or an issue so it can be linked here for everyone.

Where the folders live

Platform	Location
Windows	hd_pack/ and music_pack/ next to Resident_Evil_Gaiden__USA_.exe
Android	/sdcard/Android/data/com.capcom.regaiden/files/hd_pack/ and .../music_pack/

Both folders (and the hd_pack subfolders) are created automatically the first time you run the game, so the easiest way to find them is to launch once and then look.

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HD Texture Pack (hd_pack/)

HD textures are drawn at your monitor's resolution, on top of the Game Boy image - so they are not limited to 160x144. A 1024x1024 PNG is perfectly reasonable.

hd_pack/
  backgrounds/
    battle.png          <- pre-rendered battle background
    battle_0.png
  monsters/
    zombie_0.png        <- battle monster / zombie sprites
    monster.png
  portraits/
    barry.png           <- character dialogue portraits
    leon.png
    lucia.png

Format: PNG, RGBA. Transparency is respected, so give monsters and portraits a transparent background rather than a solid colour.

Sizing: backgrounds are stretched to the whole game viewport, so match your aspect ratio (16:9 works well). Monsters and portraits are scaled proportionally to the viewport height, so square images are easiest to work with.

Matching is by filename prefix. A background is used if its name contains backgrounds/battle, a monster if it contains monsters/zombie or monsters/monster, and so on. That means battle_starlight_corridor.png works fine - you are not limited to the exact names above.

Hot-reload: edit a PNG and press Reload HD Textures in the in-game menu (F10). No restart needed, which makes iterating on art quick.

Enable the pack with Enable HD Texture Pack in the menu. It is off by default.

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Replacement Soundtrack (music_pack/)

music_pack/
  track_1.ogg           <- replaces Battle music (ID 1)
  track_10.ogg          <- replaces Title Screen (ID 10)
  ...

Formats: .ogg (Ogg Vorbis) and .wav. OGG is strongly preferred - a three-minute WAV is about 30 MB, which adds up fast, especially on a phone. Any sample rate and channel count works; files are converted to 44.1 kHz stereo when loaded.

Naming: track_<id>, where <id> is the game's own music ID (from 1 to 27). Tracks then follow the game automatically - the right music plays in the right place, and any ID you have not supplied simply keeps the original Game Boy music. That means you can replace one track and leave the rest alone.

[!NOTE] Track 0 is reserved for silence/stop: During room transitions and scene fades, the sound driver sets the music register to 0 (silence). Do NOT name any music track_0.ogg, as it is not a playable track.

Finding or verifying track IDs:

1. Open the in-game menu (F10 on desktop, the gear icon on Android)
2. Go to the HD Pack tab
3. The menu always displays Current Game Track: ID N (Name) regardless of whether a custom track is playing or not.
4. Name your file track_N.ogg and click Reload Music Pack to test it immediately without restarting.

Track ID Index

Track ID	Description / Scene
0	Silence / Stop / Room Transitions (Reserved - not a playable track)
1	Battle
2	Introduction (Part 1 - Capcom & Legal disclaimers)
3	Introduction (Part 2 - Virgin Interactive & M4)
4	Introduction (Part 3 - In-game Intro Cutscene)
5	Restaurant
6	Restaurant (Alternate Loop)
7	Restaurant X
8	Prologue / Cutscenes
9	Unused / Silence
10	Title Screen
11	Side Deck
12	Side Deck X
13	Main Hall X (Variation)
14	Side Deck X (Mild Drums)
15	Main Hall
16	Main Hall (Slower, No Bass)
17	Main Hall X
18	Title (Battle Version)
19	Zombie Attack
20	Class Cabin
21	Class Cabin X
22	Class Cabin (With Bass)
23	Corridor
24	Corridor X
25	Corridor X (Variation)
26	Corridor X (No Drums, Slower)
27	Class Cabin (With Bass & Drums)

Seamless Loop Point Support

Custom tracks can loop seamlessly from a designated loop point (skipping the song's intro on loop repetitions). Loop points can be configured in 3 flexible ways:

1. WAV Files (smpl Chunk): Standard sampler loop points embedded by digital audio workstations (DAWs) like FL Studio, Reaper, Wavosaur, Audacity, GoldWave, etc., are detected automatically.
2. OGG Vorbis Comments: Standard comment tags like LOOPSTART (or LOOP_START) and LOOPEND / LOOPLENGTH (or LOOP_END / LOOP_LENGTH). Supports integer sample offsets, seconds (e.g. 3.292s), or MM:SS.mmm timestamps.
3. External music_pack.ini: Create a plain text music_pack/music_pack.ini file (or track_<id>.ini) to set loop points without needing an audio editor:

   [track_10]
   loop_start = 3.292s
   loop_end = 85.5s
   
   [track_1]
   loop_start = 145200
   

When loop points are present, the in-game menu (F10) displays the detected loop range ([Loop: 00:03.29 -> 01:25.50]).

Sound effects. Game Boy music and SFX share the same four audio channels, so there is no way to mute only the music. The emulated audio is turned down instead, which keeps gunshots, doors and menu blips audible under your track. Two sliders control the balance:

• Music Volume - how loud your replacement track is
• Game Audio While Music Plays - how loud the original Game Boy audio stays (default 25%). Lower it for less of the original melody bleeding through; raise it to keep sound effects punchier.

Looping is on by default, so short tracks repeat rather than falling silent.

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Getting your files onto Android

Everything lives in the app's external storage folder, which is reachable without root:

/sdcard/Android/data/com.capcom.regaiden/files/
    hd_pack/
    music_pack/

Run the game once first - that creates the folders.

• USB from a PC: connect the phone, set the USB mode to File Transfer / MTP, then browse to Internal storage > Android > data > com.capcom.regaiden > files and copy your hd_pack / music_pack contents in.
• On the device: most file managers can reach Android/data directly. On Android 11+ some stock file managers restrict it - if yours does, use a manager that supports the Storage Access Framework picker, or copy the files over USB.
• ADB:

  adb push music_pack/. /sdcard/Android/data/com.capcom.regaiden/files/music_pack/
  adb push hd_pack/.    /sdcard/Android/data/com.capcom.regaiden/files/hd_pack/
  

After copying, either restart the game or use Reload HD Textures / Reload Music Pack in the menu.

The same folder is also where state snapshots are written if you use the diagnostics button, which makes them easy to pull off the device and attach to a bug report.

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Controls

Keyboard Defaults

Action	Primary Key	Secondary Key
Move Up	W	Up Arrow
Move Down	S	Down Arrow
Move Left	A	Left Arrow
Move Right	D	Right Arrow
A / Confirm / Shoot	Z	J
B / Cancel / Run	X	K (Hold while moving to Run)
Dash / Sprint (Dedicated)	Left Shift	Right Shift
Select / Map	Backspace	Tab
Start / Inventory	Enter	-
In-Game Settings Menu	F10	Escape
Quick Save State	F5	-
Quick Load State	F8	-
Previous / Next Save Slot	F6	F7
Fast Forward	Tab	-
Toggle Max Speed	` (backtick)	-
Toggle Mute	M	-
Performance Overlay	F1	-
Capture State Snapshot	F4	-

Gamepad Defaults (Xbox / PlayStation)

Action	Xbox Button	PlayStation Button
Movement	D-Pad / Left Stick	D-Pad / Left Stick
A / Action	B	Circle
B / Cancel	A	Cross (Hold while moving to Run)
Dash / Sprint (Dedicated)	Right Shoulder (RB)	R1 / L1
Select	Back / View	Share / Select
Start	Start / Menu	Options / Start
In-Game Menu	Left Stick Click (L3)	L3
Quick Save	X	Square
Quick Load	Y	Triangle
Fast Forward	Right Trigger (RT)	R2

The face buttons follow the Nintendo layout: the right-hand button is Game Boy A, so on an Xbox pad that is the B button. All bindings are remappable in the in-game menu. On Android, a dedicated on-screen >> sprint button is placed above the virtual B button.

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Building from Source

Prerequisites

• CMake (3.15 or newer)
• C/C++ Compiler: Clang, GCC, or MSVC (Visual Studio 2022) with C11 and C++20 support
• Ninja or MSBuild
• SDL2 Development Libraries (included in deps/)

Build on Windows

# Clone the repository
git clone https://github.com/sergiomanzur/regaiden-recomp.git
cd regaiden-recomp

# Build with static CRT and package Windows release
.\scripts\package_release.ps1 -Version "0.4.0" -SkipAndroid

Build on Android (APK)

# Navigate to Android directory
cd android

# Compile ARM64-v8a debug APK
.\gradlew assembleDebug

The resulting APK is generated at android/app/build/outputs/apk/debug/app-debug.apk.

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ROM Compatibility & Legal Notice

This repository contains only clean-room reverse-engineered recompilation source code, runtime wrappers, shaders, and original mod assets. It does NOT contain copyrighted game ROMs, proprietary audio, or commercial Game Boy Color assets.

To play, provide a legally acquired ROM dump of:

• Title: Resident Evil Gaiden (USA)
• Format: .gbc
• Expected Size: 2,097,152 bytes
• Expected SHA256: 9a97678cbd8da02c8763e977674e17f460c06ea8b73bad35c52fe6817f506d44

Place Resident Evil Gaiden (USA).gbc in the root directory (Windows) or select it via the in-game ROM setup picker on first launch (Android / Windows).

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License

• Source code: MIT License
• Dear ImGui: MIT License
• stb_image: Public Domain
• SDL2: zlib License

Resident Evil and Resident Evil Gaiden are registered trademarks of Capcom Co., Ltd. and Virgin Interactive. This project is an independent open-source recreation for preservation and modern enhancement purposes.