Humble Indie Bundle 2:
  Braid
  Cortex Command
  Machinarium
  Osmos
  Revenge of the Titans

Micro Potato Pack:
  Audiosurf
  Defense Grid
  Rush

Half-Life 1 Mega Pack:
  Counter-Strike
  Counter-Strike: Condition Zero
  Day of Defeat
  Deathmatch Classic
  Half-Life
  Half-Life: Blue Shift
  Half-Life: Opposing Force
  Half-Life: Source
  Ricochet
  Team Fortress Classic

Counter-Strike: Source

Day of Defeat: Source

Half-Life 2

Half-Life 2: Deathmatch

Half-Life 2: Episode One

Half-Life 2: Episode Two

Left 4 Dead

Left 4 Dead 2

Portal

Post Apocalyptic Mayhem