Other things you ought to take a look at:

Sauerbraten in JS, called Bananabread¹, and jor1k an OpenRISC emulator running Linux². Although the latter uses a relay for networking.

1: https://developer.cdn.mozilla.net/media/uploads/demos/a/z/az...

2: https://s-macke.github.io/jor1k/demos/main.html