Here's my list, but I'm sure I'm leaving something out.
BTW: Ghost Recon is hard to put down.
There is almost no finishing it because more maps are downloadable. You want a game that will last almost forever? Get all the Ghost Recons. You can play the maps alone or online with others. In fact, I've been playing Ghost Recon daily for over a year. Being disabled that means almost nightly. It really never gets old.
I normally get all my games through STEAM. (especially when they are on sale) I rarely pay full price.
I don't need to be first on the block to play the game. (except for the HalfLife episodes, I can't wait for the final Episode 3) I simply love Alyx Vance(Merie Dandridge):
http://www.jsamples.com/alyx/alyx_vance.html Angle of Attack
BattleStations
Braid
Battle Grounds 2
BattleField 2
Castle Wolfenstien
Return to Castle Wolfenstien
Call of Duty
Counter Strike
Darkest Hour
Day of Defeat
DOOM 1 , 2, and 3
Duke Nukem
Dystropia
Eternal Silence
EVE Online
F.E.A.R. 2: Project Origin
Half-Life
Half-Life 2 - DeathMatch
Half-Life 2 - Episode One
Half-Life 2 - Episode Two
Half-Life 2 - Lost Coast
Half-Life - Blue Shift
Half-Life - Opposing Force
Left 4 Dead
Left 4 Dead 2 (Playing now)
Mare Nostrum
Red Orchestra: Ostfront
S.T.A.L.K.E.R: Clear Sky
Team Fortress Classic
Tom Clancy's Ghost Recon (installed more maps - still playing)
Tom Clancy's Ghost Recon: Advanced Warfighter (installed more maps - still playing)
Tom Clancy's Ghost Recon: Advanced Warfighter2 (installed more maps - still playing)
Tom Clancy's Ghost Recon: Desert Seige
Tom Clancy's Ghost Recon: Island Thunder
Tom Clancy's Ghost Recon: H.A.W.X.
Tomb Raider: Anniversary
Tomb Raider: Underworld
Warhammer
QUAKE 1, 2, 3, 4
Combat Flight Sim WWII Europe
Combat Flight Sim 3 Battle for Europe
Falcon F-15
Falcon 4.0
Microsoft Flight Sim 1998
Microsoft Flight Sim 2000
Pro Pilot 99