Half-Life 2 is a first person shooter video game created by the company Valve Corporation and released in 2004. This game is the sequel to the original Half-Life video game which came out in 1998. It is sold through the "Steam" sales system also developed by Valve. (Steam is a gaming platform where all games made by Valve can be played.) It is also available in The Orange Box, along with and (sequels to Half-Life 2), Portal, and Team Fortress 2. is currently in development. Half Life 2 is based on a game engine called Source. There have been many other Source-based games, such as Portal, Team Fortress 2, , and Garry's Mod.