I'll list them all left to right, top to bottom:
CoD1, CoD4, Heretic, Quake4, RollerCoasterTycoon3, SeriousSam2
Left4Dead, TrackManiaUnited, Quake1, Portal1, PeggleExtreme, Quake2
HalfLife

posingForce, Gmod, HalfLife2, EnemyTerritoryQuakeWars, HalfLife, DukeNukem3D
Doom3, Doom1, HalfLife:BlueShift, LegoRockRaiders, BattlefieldBadcompany2, GrandTheftAuto:SanAndreas
Black&White, UnrealTournament3, Black&White2, RollerCoasterTycoon2, Spore:GalacticAdventures, Pharaoh
Command&Conquer:Generals:ZeroHour, Minecraft, Starcraft2, UnrealTournament2004, Quake3, Battlefield1942
And I'm not sure my SC2 username and stuff because I can't play any online games here at uni so I haven't been on in a while. (They're blocking like every port but the bare minimum D: )
EDIT:
Lol at OposingForce having a
in the name. 
Slike, OMG!posingForce
EDIT2:
Of course, there were always games I couldn't find a place for on my desktop background that have icons on my quicklaunch:
Battlefield2, BattlefieldHeroes, CrayonPhysics, Creatures2, Demonstar, DwarfFortress, OpenTransportTycoonDeluxe, Starcraft1, TotalAnnihilation, TrackManiaNations, Wonderland Adventures