And for a somewhat more practical but at the same time more exotic example, the Internet Archive has a ton of old minicomputers and arcade games running in MESS/MAME, each compiled to webasm. One click and you can boot anything and play it in your browser. https://archive.org/details/softwarelibrary
Are you sure that's actually using WASM? It sounds to me like it's currently using ASM.js compiled via Emscripten. (Though in theory there's no reason why it _couldn't_ be WASM, since Emscripten supports WASM as a compiler target.)
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