I highly recommend both Paul Graham's source code for Arc (http://ycombinator.com/arc/arc3.tar http://ycombinator.com/arc/arc3.tar), as well as the source code

I highly recommend both Paul Graham's source code for Arc (http://ycombinator.com/arc/arc3.tar http://ycombinator.com/arc/arc3.tar), as well as the source code for Quake and Quake II (http://www.idsoftware.com/business/techdownloads/ http://www.idsoftware.com/business/techdownloads/).