What I have on this one account:
Half-Life 1 (with Counter-Strike, DoD, TFC, HL:DM, Ricochet, Blue Shift, OpFor)
Half-Life 2
HL Ep 1 and 2
HL Source and HL:DM Source
Counter-Strike: Condition Zero and Deleted Scenes
Counter-Strike Source
Day of Defeat Source
Team Fortress 2
Left 4 Dead
Portal...