You're likely referring to —a project that emulates Nintendo 64 games in a web browser via WebAssembly.
The standout example is by Paul Holden (and similar work by other emulator devs). It ports a stripped-down Mupen64Plus or similar core to WASM, using SDL + OpenGL ES via WebGL for graphics, audio resampling to avoid latency issues, and often dynamic recompilation (or interpreter fallback) for MIPS→WASM translation. n64 wasm
Would you like a deeper dive into the recompiler implementation or graphics pipeline? You're likely referring to —a project that emulates