Play classic DOOM directly inside Visual Studio Code using WebAssembly. Powered by Websockets Doom — a Chocolate Doom port compiled to WASM via Emscripten. Uses FreeDOOM game data (downloaded automatically on first run). Commercial WADs are also supported.

Search terms: doom, vscode doom, doom extension, chocolate doom, freedoom, wad, webassembly, retro fps.

DOOM for VS Code

Play!

Ctrl+Shift+P  →  DOOM: Play DOOM 🔫

FreeDOOM (~56 MB) is downloaded automatically on first run and cached locally. Subsequent launches are instant.

Controls

Key	Action
`W` / `↑`	Move forward
`S` / `↓`	Move backward
`A` / `←`	Turn left
`D` / `→`	Turn right
`Alt` + `A` / `D`	Strafe
`Shift`	Run
`Ctrl`	Fire
`Space` / `E`	Use / Open door
`Tab`	Automap
`Esc`	Menu
`1`–`7`	Select weapon
Mouse	Look / aim (click the canvas to capture)

Settings

Open with Ctrl+Shift+P → DOOM: Configure WAD File, or edit your VS Code settings.json:

Setting	Default	Description
`doom.wadPath`	`""`	Absolute path to a custom `.wad` file. Leave empty to use auto-downloaded FreeDOOM.
`doom.enableSound`	`true`	Enable sound effects. Disable if you experience audio issues. Note: music is always off (see Known Limitations).

Developer notes

Using a Commercial WAD

If you own Doom 1 or Doom 2 (available on Steam or GOG):

// settings.json
"doom.wadPath": "C:/path/to/your/doom.wad"

Any IWAD compatible with Chocolate Doom works: doom.wad, doom2.wad, tnt.wad, plutonia.wad.

Known Limitations

No music — MIDI / OPL music initialisation can hang in a browser WebAudio context in this build. Music is disabled by default (-nomusic flag). Sound effects work fine.
No save games — Emscripten's virtual filesystem is in-memory. Saves are lost when the panel is closed.
Mouse capture — Click the canvas to capture the mouse for mouselook. Press Esc to release. VS Code may show a "pointer captured" indicator in the status bar.
One panel at a time — Running the command when a DOOM panel is already open just brings it to focus instead of starting a second instance.

Architecture

doom-extension/
├── src/
│   ├── extension.ts      — activate(), registers doom.play + doom.configureWad commands
│   ├── DoomPanel.ts      — WebviewPanel singleton; generates the HTML page with canvas
│   └── wadManager.ts     — Downloads FreeDOOM WAD to globalStorageUri on first run
├── media/
│   ├── websockets-doom.js    — Emscripten JS glue (Chocolate Doom, not included)
│   └── websockets-doom.wasm  — Compiled Chocolate Doom WASM binary (not included)
└── scripts/
    └── fetch-doom-assets.js  — Helper script to download engine assets automatically

How it works

doom.play command fires → wadManager.ensureWad() checks / downloads FreeDOOM
DoomPanel.createOrShow() opens a WebviewPanel with a canvas and a start-screen overlay
User clicks ▶ PLAY DOOM → AudioContext is created (browser autoplay policy requires a user gesture)
window.Module is configured with Emscripten options, then websockets-doom.js is injected via <script>
WASM compiles, FreeDOOM WAD is fetched into Emscripten's virtual filesystem
onRuntimeInitialized fires → global callMain(['-iwad', 'freedoom1.wad', '-window', '-nogui', '-nomusic', ...]) starts the engine
Chocolate Doom renders into the <canvas> via SDL2 → WebGL; audio via Web Audio API

Key VS Code WebView constraints solved

Challenge	Solution
No `SharedArrayBuffer` in webview	Websockets Doom uses a single-threaded Emscripten build — no COOP/COEP headers needed
Emscripten uses `eval()`	CSP includes `'unsafe-eval'` in `script-src`
WASM file path wrong in sandboxed iframe	`Module.locateFile()` remaps `.wasm` → `webview.asWebviewUri()`
56 MB WAD would bloat the VSIX	Downloaded to `context.globalStorageUri` on first run
AudioContext autoplay blocked	`AudioContext.resume()` called inside the click handler of the Play button
`callMain` is a global, not on `Module`	Call bare `callMain(args)` — this build never assigns it to `Module`
Canvas context poisoning	Never call `canvas.getContext('2d')` — SDL claims the canvas for WebGL; requesting 2D first locks it and prevents WebGL from initialising
Music hanging engine	Always pass `-nomusic`; OPL/MIDI init stalls in browser WebAudio

License

Extension code: MIT
FreeDOOM: FreeDOOM License (freely redistributable)
Chocolate Doom / Websockets Doom: GPL-2.0

This extension does not bundle the DOOM engine or any WAD files. Engine assets (websockets-doom.js / .wasm) must be provided separately. FreeDOOM game data is downloaded from the official FreeDOOM GitHub releases.