DOOM — Kotlin Multiplatform

A faithful port of the original DOOM (1993) engine to pure Kotlin, running on Android, iOS, Web (Wasm), and Desktop from a single codebase with Compose Multiplatform.

▶ Play it in your browser: kunal26das.github.io/doom

This is a line-by-line translation of id Software's released engine source (linuxdoom-1.10), preserving the original renderer (BSP, visplanes, fuzz effect, screen-melt), the complete game simulation (all monsters, weapons, sector specials), menus, HUD, status bar, automap, intermissions, finales, cheats, demo playback, and savegames — including the original engine's bugs, because demo playback desyncs without them.

What's inside

Engine	composeApp/src/commonMain/kotlin/doom/engine/ — pure common Kotlin, no platform APIs
Data tables	machine-generated from the original C (states, mobjinfo, trig LUTs, strings)
Platform layer	Compose UI, keyboard/touch input, PCM audio (AudioTrack / AVAudioEngine / javax.sound / Web Audio), storage
Game data	DOOM1.WAD — the freely-distributable shareware episode (Knee-Deep in the Dead)

Porting conventions are documented in PORTING.md.

Building & running

Requires JDK 17+. The Android SDK / Xcode are only needed for their respective targets.

# Desktop (macOS/Windows/Linux)
./gradlew :composeApp:run

# Web (Kotlin/Wasm) — opens a dev server
./gradlew :composeApp:wasmJsBrowserDevelopmentRun

# Android
./gradlew :androidApp:installDebug

# iOS — open iosApp/iosApp.xcodeproj in Xcode, set your team, run

Controls

Original DOOM bindings on desktop/web: arrows move/turn, Ctrl fire, Space use, Shift run, Alt strafe, ,/. strafe left/right, 1–7 weapons, Tab automap, Esc menu, F2/F3/F6/F9 save/load, +/- view size, F11 gamma. Type the classic cheats (iddqd, idkfa, idclev31, …) during play.

On phones/tablets: left virtual stick (move + strafe), drag right half to turn, on-screen FIRE / USE / weapon-cycle / RUN / MAP / ESC buttons.

Game data & licensing

• Engine: derivative of id Software's DOOM source, released under the GNU GPL v2 — this project is likewise GPL-2.0 (see LICENSE). DOOM is a trademark of id Software LLC; this project is not affiliated with or endorsed by id Software.
• Shareware WAD: doom1.wad (v1.9) is the shareware episode, which id licensed for free distribution. The retail episodes and DOOM II data remain commercial products — buy them (they're on Steam/GOG) and the engine will happily run doom.wad / doom2.wad.