If you're looking to play Q3 CPMA I have to recommend you check out Reflex. It's everything I've always wanted from an arena shooter. Incredibly smooth low latency gameplay with perhaps the kindest community I've ever come across in an online shooter.
It sounds like CPMA's creator arQon hasn't been heard from in a few years, but the source code is held by at least one or two other people[0].
http://www.esreality.com/post/2839396/to-arqon-cpma-sources/...