Dota 2
July 2013
CS:GO
August 2012
Portal 2
April 2011
Left 4 Dead 2
November 2009
Left 4 Dead
November 2008
Team Fortress 2
October 2007
Portal
October 2007
Day of Defeat: Source
September 2005
Half-Life 2
November 2004

Valve’s debut title, Half-Life, was released in 1998. It won more than 50 game of the year awards, and PC Gamer even called it the best PC Game ever made. Since then, we’ve shipped a few (but not enough) Half-Life sequels, a World-War II team-based action game, a counter-terrorism game that took the world by storm, a couple games about killing zombies, and a brain-twisting puzzler in which players fold space into knots.
Oh, and TF2 .

The most recent game we've added to the list is Portal 2 . Anyway, what are you waiting for—try them out! You can pick up any of these games at your local retailer, or buy them right now for your Mac or PC, using Steam .

Source combines leading-edge character animation, advanced AI, real-world physics, shader-based rendering, and a highly extensible development environment to produce some of the most popular computer and console games.