Doom 3
Call of Duty
Half Life 2
Guild Wars

Planescape: Torment
Age of Wonders I

(turn based RPG! Yes!)

Uninstalled starship sonata recently, as well as EQ & WoW & AO

Now that I have a new (well, newer than my last post anyway) to me tablet PC for work, I'll list what is installed on it:

Guild Wars
Medieval: Total War: Viking Invasion
Fallout 2
Lands of Legend
Inkball (which probably doesn't count, but it's a fun time waster)

Let's see if I can recall everything that is installed on my rig at home:

Guild Wars
Half-Life 2
Counter-Strike: Source
Knights of the Old Republic 2
The Temple of Elemental Evil
Codename Panzers: Phase One
Ghost Recon
Ghost Recon: Desert Siege
Ghost Recon: Island Thunder
Raven Shield
Raven Shield: Athena Sword
Command & Conquer: Generals
Command & Conquer: Generals: Zero Hour
Neverwinter Nights
Neverwinter Nights: Shadows of Undrentide
Neverwinter Nights: Hordes of the Underdark
Neverwinter Nights: Witch's Wake
Neverwinter Nights: Kingmaker
Neverwinter Nights: Pirates of the Sword Coast
Neverwinter Nights: Shadowguard
Battlefield 2
Gary Grigsby's World at War
Team Fortress Classic
Warhammer 40,000: Dawn of War
Warhammer 40,000: Dawn of War: Winter Assault
Dragonshard

Battlefield Vietnam
Battlefield 2
Point of Existence
Call of Duty 2
Americas Army
NHL 06

*Half Life 2/CS:Source (never play it though)
*Civ IV
*N64 Emulator and roms
*Rollercoaster Tycoon 3

Demos -

*Fifa 06
*Serious Sam 2

Half Life 2
Half Life 2 Deathmatch
Half Life 2 Lost Coast (ok, just a tech demo but I thought I'd add it anyway)
Half Life
Half Life Source
Half Life Blue Shift
Half Life Opposing Force
Counter Strike Source
Counter Strike
Counter Strike Condition Zero
Counter Strike Condition Zero Deleted Scenes
Day of Defeat
Day of Defeat Source
Warhammer 40,000 Dawn of War
Doom 3
Doom 3 Ressurection of Evil
Guild Wars
Neverwinter Nights Platinum
Dungeon Seige 2
Call of Duty 2
F.E.A.R.
Quake 4
Battlefield 2
Battlefield 2 Special Forces
Korsun Pocket
Battles in Normandy

Well.......
 

Age of Wonders II
Baldur's Gate
Civilization IV
Diablo II
Dungeon Siege : Legends of Arranna
Neverwinter Nights (All expansions)
Master of Orion III
Birth of the Federation
Simcity 4
Temple of Elemental Evil
Tropico

And I play.....
Civilization IV and Simcity 4 the most......

Hmm, let's see...

World of Warcraft
Half-Life 2
Counter-Strike 1.6
Counter-Strike: Source
Counter-Strike: Condition Zero
Neverwinter Nights (all expansion except Kingmaker)
Unreal Tournament 2004
Vampire The Masquerade: Bloodlines
Black & White 2
Need For Speed Underground 2
Warcraft 3: Frozen Throne
Fallout Tactics
Ultimate Spider Man
Serious Sam 2
Quake 4
Dungeons & Dragons Online - Stormreach
Civilization 4
Far Cry
F.E.A.R.
lots of emulators and roms

oh, and we can't forget the king of all games, Minesweeper.