QuakeJS – A Quake Port to JavaScript with Emscripten
EDIT: This appears to have died, now that the content servers for quakejs have died. My servers are no longer starting anymore :(. For those reading on later, there was peak of 10 on both servers just before it went down  ioq3 1.36_GIT_4f7d7bf-2014-02-01 emscripten- Feb 23 2014
  ----- FS_Startup -----
  Error: Failed to download and parse manifest, Couldn't load 
  http://content.quakejs.com/assets/manifest.json. Status: 500

---Giving that at the time of viewing, the multiplayer servers are down, have some of mine:http://www.quakejs.com/play?connect%20185.230.223.84:27967http://www.quakejs.com/play?connect%20185.230.223.84:27966You will want to:Go into settings via esc and set your name, and maybe also turn the game down, it's quite loud by default. Maybe also mouse sensitivity too.