Best FPS game you have played

SUCH A DIFFICULT QUESTION! :O

Crysis takes the cake for me though, such a fluid game.

Call of Duty United Offensive (MP obviously), Call of Duty 4 with promod.

S.T.A.L.K.E.R!!

Battlefield 3

Not sure if you're asking for a favourrite FPS, but mine are Clive Barker's Jericho and Team Fortress 2 (pre-hats), and Call of Duty 2.

Counter Strike 1.6

Bioshock!

I've enjoyed mw2 or halo reach the most.

Wolfenstein: Enemy Territory and TF2

Counter Strike Source

played bf3 and bc2 but best one was bf2 and project reality

FEAR

CoD.

Bad Company 2 by far, even better then BF3

Single Player:

Half Life - Half Life 2 (Episodes included) By far the best FPS game ever created. - Call of Duty SP games (especially the Modern Warfare story) - Quake 2 - Deus Ex 1 & 3 (2 blew chunks)

Multi-Player

Battlefield series - Quake 2 - Team Fortress Classic - Counter Strike up to 1.6

DOOM 1-2, HL 1-2

crysis, stalker and cod

Minecraft :D

Deus Ex, though not a pure FPS. Still the best after all those years.

action quake 2

Tribes 2

hurr durr mw3

1.6

Borderlands like fps+rpg style :p:p

HL2 and Quake 3 (my first fps)