A port of the Cortex Command Community Project to WebAssembly: the original C++ engine, compiled with Emscripten, running in Chrome with its game data, Lua scripts, audio, saves and editors.

Play it at https://yaroslav.au/cortex-command/, deployed from main whenever every check passes (hosting).

It is built from upstream commit 20dfb3ea5, with the engine's platform layers adapted for the browser:

How each of these works, what was compared against the original and how, and where the port deliberately differs, is written up in notes/.

• Chrome 137 or newer (JSPI). Other browsers are untested.
• The page must be served with cross-origin isolation headers (Cross-Origin-Opener-Policy: same-origin, Cross-Origin-Embedder-Policy: require-corp); serve.py does this.
• Building needs macOS or Linux with git and Python 3.

tools/setup-toolchains.sh        # once: Emscripten 4.0.15 and CMake into toolchains/
./build.sh --target cortex       # the game, into dist/
python3 serve.py --port 8080     # then open http://127.0.0.1:8080/

dist/ then holds the whole app: index.html, cortex.js, cortex.wasm, cortex.data (the game data without its sounds, 52 MB), cortex.data.json (its size and SHA-256) and audio/ (the sounds, 295 MB). Opening the page downloads none of it: the start screen offers "Play Game", which downloads the program and the package the first time (the browser keeps them for later visits) and starts the game, and the sounds follow in the background once the rest has arrived. Host dist/ anywhere that sends the two headers above and lets browsers revalidate the files (Cache-Control: no-cache, as serve.py sends; a browser that kept an earlier cortex.js would not match a newer package); the test pages in it can be left out. A host that answers Range requests, as most do, lets a download that broke off go on from where it stopped.

To run every automated check (test programs, recorded outputs, the game booting and its deterministic simulation) in a fresh headless Chrome:

./build.sh --target checks
node tools/run-checks.mjs

CI runs the same on every push. ./build.sh --debug builds with Emscripten's runtime assertions into dist-debug/, and ./build.sh --worker runs the engine on a worker thread instead of the page's main thread, into dist-worker/ (it plays the same and starts about a second slower; see notes/threads.md). See notes/testing.md.

engine/      the port's copy of the engine: Source/, Data/, external/, Resources/
             (PORT-CHANGES.patch lists every change from the original)
runtime/     browser platform layers: audio, filesystem, persistence
site/        the page that loads the game
vendor/      Lua 5.1.5, LuaBitOp, miniaudio
tests/       browser test programs and their pages
tools/       toolchain setup, headless Chrome driver, comparison tools
notes/       how the port works; notes/PORT-STATUS.md is the build log
specs/       the rules the game and its page must keep (see AGENTS.md)

AGPL-3.0, the licence of the Cortex Command Community Project it is derived from (see LICENSE). The game's code and data are the Cortex Command Community Project's. Bundled third-party components keep their own licences: those that came with the engine are in engine/Licences/ and beside their sources in engine/external/; Lua and LuaBitOp are MIT (vendor/); miniaudio is public domain or MIT-0.

FMOD is proprietary (engine/Licences/FMOD.TXT). The browser build uses only FMOD's API headers, implemented here over miniaudio; the native FMOD libraries in engine/external/lib/ are upstream's, kept so the engine copy stays complete, and are not used by the browser build.