right now im waiting for quake 4 but the q4 team decided to use doom3 engine and that kinda sucks because i liked quake coders because of their good independant engines.. Quake 2 engine helped gabe newell make his "HalfLife Engine" and Quake 3 engine was used as a base for MOHAA, RTCW, ET, COD, and a few that im missing. I dont like Doom3 Engine because it uses alot of system specs, its all about graphics and not alot on gameplay/physics (although the scripting was pretty good)