Dota 2 is an action strategy title for the PC and Mac. It is being developed by Valve Corporation, and is the stand-alone sequel to a popular mod created for WarCraft III, called Defence of the Ancients (Dota), which is itself loosely based on a custom map for the original StarCraft, called Aeon of Strife.

Half-Life 2 is a shooter game developed by Valve Corporation and released on Mac OS, Microsoft Windows, PlayStation 3, Xbox.

Half-Life is a shooter game developed by Gearbox Software, Valve Software and released on Mac OS, Microsoft Windows, PlayStation 2.