Half-Life is a 1998 first-person shooter game developed by Valve Corporation and published by Sierra Studios for Windows. It was Valve's debut product and the first game in the Half-Life series. The player assumes the role of Gordon Freeman, a scientist who must escape from the Black Mesa Research Facility after it is overrun by alien creatures following a disastrous scientific experiment. The gameplay consists of combat, exploration and puzzles. Download Key:3333-33333-3333 or AAAA-AAAAA-AAAA

Half-Life 2 is a 2004 first-person shooter (FPS) game developed and published by Valve Corporation. It was published for Windows on Valve's digital distribution service, Steam. Like the original Half-Life (1998), Half-Life 2 combines shooting, puzzles, and storytelling, and adds new features such as vehicles and physics-based gameplay. The player controls Gordon Freeman, who joins a resistance to liberate Earth from the Combine, an interplanetary alien empire. Download

Portal is a single-player first-person action/puzzle video game developed by Valve. The game consists of a series of puzzles which must be solved by teleporting the player's character and other simple objects using a single handheld device, with the goal of getting to an objective point. The game was released in in a bundle package known as The Orange Box for for PC and Xbox 360 on October 10, 2007, and will be released for the PlayStation 3 sometime in November. The Windows version of the game is also available for download separately through Steam. Download

Grand Theft Auto: San Andreas is a 2004 action-adventure game developed by Rockstar North and published by Rockstar Games. It is the seventh title in the Grand Theft Auto series, following 2002's Grand Theft Auto: Vice City. Set within the fictional state of San Andreas, the game follows Carl "CJ" Johnson, who returns home after his mother's murder and finds his old gang has lost much of their territory. Over the course of the game, he attempts to re-establish the gang, clashes with corrupt authorities and powerful criminals, and gradually unravels the truth behind his mother's murder. Download