Quake III is quite intensive and runs on all platforms. Figure out how it's made. Not everything needs to be cramped into a browser frame, have an annoying log

Quake III is quite intensive and runs on all platforms. Figure out how it's made. Not everything needs to be cramped into a browser frame, have an annoying login screen and eat 20% of CPU while sitting idle. Oh, did I mention the hidden benefit of being useful offline?