What OpenOni is

OpenOni is a reimplementation of Oni, Bungie West's third-person action game from 2001, in C11. It is not an emulator or a wrapper. Every part of the game is ported function by function from the original Windows executable (Oni.exe, version 1.0), in the original's own terms: its modules, its data formats, its timing. Quirks and bugs are kept, because they are part of the game.

The game runs on gasm, a WebAssembly game runtime: one openoni.wasm that gasm runs natively on macOS, Linux and Windows, and in the browser.

OpenOni contains none of the original game's data. It reads everything (levels, textures, sounds, movies and the tables inside the executable) from your own copy of the game: see getting the game files.