I've been a "hardcore" FPS gamer since Delta Force came out back in 1999.
I love FPS, RPG, and MMO games; currently my favorites are; Battlefield 3 Beta (I hate Origin, preferred it if EA/DICE used steam.), Star Trek Online, and Second Life (fun little addictive social MMO, oh and it's free so it's double awesome ^.^).
Since a couple others have listed their games, I'll list what I can remember, since I have four large tote boxes full of PC games.
Delta Force
Delta Force 2
Delta Force: Task Force Dagger.
DF: Land Warrior.
DF: Black Hawk Down w/ Team Sabre.
DF: Extreme.
COD 1, w/ expansions.
COD 2.
CoD 4.
CoD 5.
CoD 6/MW2.
CoD 7/Black Ops.
Crysis 1/2.
Battlefield 1942, vietnam, 1943, 2142, and of course 2.
Battlefield Bad Company 2.
Fall Out 3 w/ New Vegas.
The Half-Life Series.
World of Warcraft.
The Warhammer PC Series.
Command & Conquer series.
Minecraft
Can't think of the others... But I've spent hundreds, if not thousands of dollars buying every decent game brand new in it's time over the past 12 years. Not to mention my overly expensive custom, and hand built, Gaming rig, which is already out of date by three months >.<, the spec to it I'll just elave out to save space in the post ^~^.