Tribes: Vengeance is a science fiction first-person shooter video game, developed by Irrational Games and released by Sierra Entertainment (part of Vivendi Universal) in October 2004. It was built on an enhanced version of the Unreal Engine 2/2.5, which Irrational Games called the Vengeance engine. Part of the Tribes series, in addition to its multiplayer network maps, Vengeance includes a complete single-player campaign.