This WebAssembly runtime is unique because it is implemented purely in TypeScript types, allowing you to turn C code or WebAssembly into TypeScript types without any JavaScript runtime code. Surprisingly, it can run Doom, defying expectations. The repo is described as an “active crime scene” with the murder weapon still unknown. The author, @dimitropoulos, has no intention to further develop it post-Doom success, but is open to discussions. Some remarkable types such as ShiftRight and Add are mentioned. The runtime implements various WebAssembly instructions from the spec. A noteworthy feature is the conformance tests against the JavaScript built-in WebAssembly runtime for accuracy verification.
https://github.com/MichiganTypeScript/typescript-types-only-wasm-runtime