Counter-Strike: Source (commonly shortene to CS:S) is a computer video game developed by Valve Corporation. It is a remake and update of an older version of the game, which originally started as a modification of Half-Life, a single-player first person shooter. As in the original version, Counter-Strike: Source games pit a team of counter-terrorists against a team of terrorists in a series of rounds. Each round is won by either completing a mission (such as detonating a bomb or rescuing hostages) or by eliminating all members of the opposing team. Unlike Half-Life: Source, the game is a complete remake using Valve's Source Engine, instead of a port with additional content.