Very nice! Got sucked into this very quickly and enjoying it a lot - it did freeze, so here's the error message from the console in Firefox:
>
Uncaught RuntimeError: index out of bounds
dynCall_v https://v6p9d9t4.ssl.hwcdn.net/html/3874424/WebExport/index.js:8
browserIterationFunc https://v6p9d9t4.ssl.hwcdn.net/html/3874424/WebExport/index.js:8
runIter https://v6p9d9t4.ssl.hwcdn.net/html/3874424/WebExport/index.js:8
Browser_mainLoop_runner https://v6p9d9t4.ssl.hwcdn.net/html/3874424/WebExport/index.js:8
index.js line 180 > WebAssembly.instantiate:1461026:1