Reaction 1.0 Beta is an Action Quake 2-like based on ioq3 with "freeware" BY-NC-SA assets. A list of open source Minecraft-style games was recently shared in a Reddit thread . 219 bytes tron is: <body id=b onkeyup=e=event onload= z=c.getContext('2d'); z.fillRect(s=0,0,n=150,x=11325); setInterval(" 0<x%n &x<n*n &(z[x+=[1,-n,-1,n][e.which&3]]^=1) ?z.clearRect(x%n,x/n,1,1,s++) :b.innerHTML='game⬜over:'+s ",9) ><canvas id=c> Swallow for browser-based games , as introduced in a AltDevBlogADay post , is: A directory scanner which packages files into a single JSON file A small part of your build chain