haha most will say counter strike but not me. Any of the Quake series is and will always be my favorite. Back then everyone could move and shoot at full speed you had to predict where your opponent would be next or lead them to where you want them to be. Counter strike ruined fps gaming in a way. Always one person is standing still while the other is moving its very one sided and took away a lot of the challenge. If anyone watches an old school pro series Quake matches they will see a huge difference. Also counter strike is more of a team fps and Quake could be 1vs1.