Gauntlet: Dark Legacy in Rust

Gauntlet: Dark Legacy — Rust Engine

A from-scratch Rust/Bevy runtime for the GameCube release of *Gauntlet: Dark Legacy* (game ID GUNE5D), built from reverse engineering the original main.dol with Ghidra and reading public technical references on the GameCube disc/DOL format.

The goal: a 1:1 rewrite — every level, monster, boss, item and mechanic working exactly as in the original — plus convenient extras the original never had: online co-op for up to four players with invite codes (each with their own camera, or the classic overhead one), Windows, macOS and Linux builds, widescreen, rebindable keyboard and mouse or any pad (switch at will), and reading your disc image directly. How close it is today is under Progress.

This project ships no game assets and no code copied from the original binary. Point it at a copy of the game you already own and it reads that copy's own data at runtime.

Download

Ready-to-run builds for Windows, macOS and Linux are on the Releases page: unzip, run gdl-game, and pick your own copy of the game when it asks.

Which copy of the game you need

The original USA GameCube release, Rev 0: game ID GUNE5D, disc revision 0 (Redump #7032). Everything here is checked against it. A full disc image of it matches:

The later USA Rev 1 (Redump #70030, also GUNE5D) and the European release (DL-DOL-GUNP-EUR, Redump #16413) haven't been tested: they load with a warning. Online, every player needs the same game ID and revision. To check yours in Dolphin: View → List Columns → Revision shows the revision, and right-click → Properties → Verify computes the hashes.

Progress

How close the rewrite is to the original GameCube game, judged area by area against the original's own code (docs/STATUS.md has the details and the full to-do list):

Beyond the original

• Online co-op for up to four players over the internet: invite codes,

  no port forwarding, each player with their own screen, camera and settings, watching a teammate while down. Friends can join a game under way, heroes can be changed mid-game, and if the machines ever disagree the level simply starts again for everyone.

• Optional first-person view, independently chosen by each player:

  animated equipped weapons and hands, mouse/right-stick look, throws that go where you look, and local split screens when needed.

• Windows, macOS and Linux; any window size, widescreen included.
• Keyboard and mouse with rebindable keys, or any pad — each player can

  switch between them at will.

• Reads your disc image directly (.iso, .gcm, .rvz) or an extracted

  folder.

Still to do, biggest first

1. Play every level from start to exit and finish the level-by-level audit

   (47 of 67 levels left): levers, lifts, doors and keys all working.

2. Monsters: several AIs still use a stand-in chase; monsters don't yet push

   each other.

3. Bosses: missile lifetimes, the blast areas' hit guards, head stumps and

   look nodes (grabs, the lich's aura, the health meters and the key are in).

4. Screens: options, the memory card screens, the attract mode and the

   ending movies (the shop, inventory, after-level screens, the levels' loading maps and opening movies are in).

5. Effects: texture wipes, effect lights, weapon and hand glows, exact

   particle maths.

6. Audio: music switching and ducking.
7. Co-op: co-op combos (decoded, not yet ported), the monsters' crowd

   penalty.

Play

PLAYING.md is the players' guide: starting the game, local co-op, and online co-op (Title → Start → Online Game → Host / Join, the invite code through the clipboard). tools/package.sh builds a release zip for this machine; the build GitHub workflow builds Windows, macOS and Linux ones.

Run

cargo run -p gdl-game

On first launch a file picker asks for your game. Any of these work:

• the disc image — .iso / .gcm, or Dolphin's compressed .rvz

  (read directly, no conversion)

• an extracted disc folder (plain extraction, or Dolphin's

  Extract Entire Disc sys/ + files/ layout)

• the extracted main.dol

It checks it's really Gauntlet: Dark Legacy, remembers the choice, and loads everything from there. Next launch goes straight in.

You can also pass the game directly, which is remembered too:

cargo run -p gdl-game -- "/path/to/Gauntlet - Dark Legacy (USA).iso"
cargo run -p gdl-game -- "/path/to/Gauntlet - Dark Legacy (USA).rvz"
cargo run -p gdl-game -- --level levelC1   # pick a level
cargo run -p gdl-game -- --forget          # forget the remembered game

GAUNTLET_GAME works in place of the path argument.

A character viewer shows any player class or monster with its animations ([ / ] action, Tab next character):

cargo run -p gdl-game -- --viewer --character KNI --action RUN1
cargo run -p gdl-game -- --viewer --monster LICH

Dolphin's other compressed formats (.gcz, .wia, .ciso, and RVZ made with bzip2/LZMA instead of the default Zstandard) aren't supported — convert to RVZ or ISO in Dolphin (right-click → Convert File…).

Your game files are only ever read. The remembered path lives in gdl-artifacts/settings.txt and the options (master, music and effects volume) in gdl-artifacts/options.txt, next to the executable (override the folder with GDL_ARTIFACTS).

Status

Boots straight from your disc (ISO or RVZ), validates all 67 levels, and plays them in 3D with the game's own geometry, textures, baked lightmaps, blending (additive glows, fog cards) and camera-facing foliage. The level's own music plays.

A hero (Warrior by default; --character VAL --variant RED for others) starts on the level's start point and runs around with the game's own speeds, turn rate, stride animations and collision (walls, ledges, steps), at its 30 Hz tick with smooth interpolation. The camera is the game's: it follows the level's own camera points and distances.

Options → Controls has the game's own control styles (with its controller diagram), rumble, auto aim and auto attack. Options or Settings → PC Settings rebinds the keyboard, mouse and pad, and has video (full screen, vsync) and debug switches; everything is saved with the options. An Xbox pad works out of the box: A attack, Y power attack, X turbo/defend, B magic, LT/LB charge, RT strafe, RB combo move, Start pause, D-pad power menu.

Developer keys, only with GDL_DEV_KEYS=1 or PC Settings → Debug → Developer Keys (the original has none, and they sit among the controls, so a stray press would change the game):

A bare run opens on the game's title screen (the game's own fonts and art), then character select, and the tower; --level or --character go straight into play. Esc/Start pauses (Settings → Audio has the volume sliders). In the tower, Manage Character → Save keeps the hero (level, gold, keys, potions, runestones, crystals and the realms beaten), and Load on the select screen brings it back; a file stands in for the memory card (docs/frontend.md, "Saving").

Generators pour out the realm's own monsters, which chase, shoot arrows, lob bombs and hit the hero, crying out as they're hit and die; the hero fights back with the game's combos, finishers, throws, turbo attacks and target search, earning experience and levels. Wounded monsters hit softer, broken generators weaken and vanish. The hero keeps the game's health, gold, keys, potions and powerups; pickups, keyed doors, exits and transporters work. Switches and pads raise elevators, drop trap walls, show bridges and run lifts that carry the hero; spikes, flame vents, force fields and saw blades cycle and hurt; barrels break open (dropping what they hold) or explode, and secret walls can be broken.

Not yet: co-op, the shop and inventory, the legendary weapons, and multi-part bosses such as the chimera (the other bosses are untested). docs/INDEX.md has what's confirmed.

Environment switches for testing: GDL_SCREENSHOT=out.png (with GDL_SHOT_AT=) saves a screenshot and exits, GDL_STICK=x,y holds the stick, GDL_FREE_CAMERA=1 starts in the free camera, GDL_WARP="x,y,z" (start the hero there), GDL_LIST_NEAR="x,y,z" (log level objects near a point), GDL_LOOK_AT="x,y,z[,distance[,yaw]]" (pin the camera on a point; yaw in degrees turns it round from −Z), GDL_PARTICLE_TEST= (that particle record 6 units ahead of the start), GDL_POTIONS=n (potions at level start), GDL_TOUR= (move to the next level every that many seconds; GDL_TOUR_STEP=0 reloads the same one), GDL_MEMSTATS=1 (logs entity and asset counts every 2 s), GDL_SAVE_DIR= (where characters.ron is kept), GDL_KEYS=n and GDL_CRYSTALS=":,…" (start with keys or crystals), GDL_MENU="start@60,down@70,accept@80" (press front-end buttons on those frames), GDL_MUTE=1 (silence this run; the saved volumes stay), GDL_SHOT_CLOCK=ticks (count GDL_SHOT_AT/GDL_SHOT_EVERY in 30 Hz game ticks, so shots land on the same moment of play every run), GDL_THROWER=,, (a grunt in front of the hero, e.g. 15,0x12,6 a suicide runner), GDL_FPS=1 logs the frame rate, GDL_BUTTONS=attack@20-21,power holds buttons, GDL_DUMMY=4 places a practice target, GDL_DEBUG_HUD=1 shows the developer overlay.

Crates

Development

GDL_SCREENSHOT=out.png cargo run -p gdl-game renders a few frames, saves a screenshot and exits. cargo run -p gdl-formats --example audio_dump -- STREAMS/CASTLE1.ads out.wav (or a .VBK and an output folder) decodes game audio to .wav. Tests that need game data use your own copy via GAUNTLET_DISC / GAUNTLET_ASSET_ROOT and skip cleanly without it.

Reverse engineering

main.dol is analyzed with Ghidra (12.1.4) using Cuyler36/Ghidra-GameCube-Loader for the DOL loader and its bundled Gekko/Broadway PowerPC SLEIGH language. Findings live in docs/, one file per system, written as they're confirmed against the actual binary — not guessed from similarly-shaped games.

License

Gauntlet: Dark Legacy and all related assets, trademarks and intellectual property belong to their respective owners. This project is unaffiliated with them.

How it was made

Made with Anthropic's Claude Opus 5.5 at max effort ("ultracode") in Claude Code, working with multiple subagents side by side: reverse engineering the original main.dol, writing the engine, and testing every level, local co-op and online play.

Legal

A fan project, not affiliated with or endorsed by Midway, Warner Bros. Interactive or Nintendo; Gauntlet and Gauntlet: Dark Legacy belong to their owners. The code is MIT-licensed (LICENSE); no game data is included or distributed — you need your own copy of the game.