Well I have a few games, most of which I haven't even played.
Alien Swarm
Counter-Strike
Counter-Strike: Condition Zero
Counter-Strike: Condition Zero Deleted Scenes
Counter-Strike: Source
Day of Defeat
Day of Defeat: Source
Deathmatch: Classic
Half-Life
Half-Life 2
Half-Life 2: Deathmatch
Half-Life 2: Episode One
Half-Life 2: Episode Two
Half-Life 2: Lost Coast
Half-Life Deathmatch: Source
Half-Life: Blue Shift
Half-Life: Opposing Force
Half-Life: Source
Hidden: Source
Left 4 Dead
Neotokyo
Portal
Ricochet
Sins of a Solar Empire
Sins of a Solar Empire: Entrenchment
Team Fortress 2
Team Fortress Classic
Trackmania Nations Forever