I'm not an FPS kind of guy, but I really enjoyed Project Snowblind. The gameplay variety was superb. You'd lead a massive assault with huge numbers of soldiers on an enemy compound in one mission, then find yourself sneaking alone through a top-secret base in the next one. And let's not forget the augmentations: slow down time, put up a peronal shield, stun foes with an electric pulse, and send them flying with a super-strong punch.

And the weapons! My favorite weapon in Snowblind, and my nominee for The Most Useful Weapon Of All Time, is the Icepick. Witht his bad boy, you can hack into computer consoles and ake control of robots. So, if the next room has a heavily-armed robot mech in it, you don't have to use ammo destroying it. Just hide where it can't see you and shoot it with the Icepick. Presto! You're in control of the robot, and can cackle with glee as you mow down hapless soldiers. When they're gone, just walk the robot to the far side of the room, sever the connection, and exit the room.

Call of Duty 4 cause it's the only one I have. But I do love COD4!!! RTS!!!!!!!!!!

oh and Phalnax811 is not a real boy

Best pure FPS: Half Life 2 and it's subsequent episodes.

Best Tactical FPS: Rainbow Six Raven Shield and its expansions (the last real Tom Clancy game, sadly)

Best Multiplayer FPS: Team Fortress 2

Red Orchestra would be a close second, or tied with even.

I have a question for you people who plays FPS religiously.  That is, how do you deal with motion sickness when playing FPS.  Oh my god, half an hour of half life 1 and i want to put my head into the toilet for puking. 

I tried playing serious sam 2, and i am telling you..the feeling of nasuea was not fun.