gasmWrite a game once. Run it everywhere.

Games compile to one WebAssembly file. Small native and browser runners give them a stable interface for graphics, sound, input and networking.

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How it works

One artifact

A game is a single .wasm file. The same bytes run in a native window (wasmtime + wgpu), in any WebGPU browser, and headless in Node for CI.

A small, stable ABI

A small core (video, audio, input, assets, params), plus optional GPU, network and storage modules. A new runner is weeks of work, not years.

3D via WebGPU

gasm:gfx is a compact WebGPU subset with WGSL shaders. Browsers forward it almost 1:1; natively it runs on Metal, Vulkan and D3D12 through wgpu.

Online multiplayer

gasm:net gives every runner WebSocket-style messaging. The sumo demo plays lockstep matches between native and browser players through a tiny relay.

Bit-exact determinism

The same inputs produce the same frames, sounds and game state on every engine, and CI checks it with hashes. That's the basis for replays, tests and netplay.

Sandboxed by design

Games only see their own memory and the ABI. No filesystem, network only with the player's opt-in, and every pointer and handle is checked.

What's inside


Runners	`gasm-run`: native (Rust: wasmtime, wgpu, winit, cpal, gilrs), with AOT compilation for no-JIT platforms. Browser runner: WebAssembly, WebGPU, AudioWorklet, Gamepad API. Headless Node runner.
Games	Sumo: 3D two-player arena with lockstep netcode. NES: a complete emulator (tetanes-core) passing the blargg CPU, timing and APU tests. Triangle and test pattern: minimal examples in Rust and C.
Tools	`gasm-relay` (WebSocket rooms), the `gasm` Rust crate, `gasm.h` for C, cross-runner determinism and network test suites.

Performance

Measured on an Apple M1 Pro. The NES emulator compiled to wasm runs at 1.5× (wasmtime AOT) and 1.6× (V8) the time of the same Rust code built natively. That's about 9× faster than the console itself. Sumo holds 60 fps with 4× MSAA on both runners.

Status

gasm is a proof of concept. ABI v0 is experimental and will change. See the roadmap: rollback netplay, storage, textures, and a wasm2c runner for consoles.