Counter-Strike: Source is a team-based tactical first-person shooter and a remake of the original Counter-Strike built on Valve's Source engine. A team of Counter-Terrorists faces a team of Terrorists across a series of rounds, each won by completing an objective such as defusing a bomb or rescuing hostages, or by eliminating the opposing team. Eliminated players do not respawn until the next round, and moving while firing reduces accuracy, encouraging careful positioning. The Source engine added interactive physics objects, ragdoll effects, and higher-detail environments, and the game was later succeeded by Counter-Strike: Global Offensive.