SWAT 4 is a tactical first-person shooter video game developed by Irrational Games and published by Vivendi Universal Games on April 5, 2005. It was built on Irrational Games's Vengeance Engine powered by Unreal Engine 2 technology. In SWAT 4, the player leads a SWAT tactical element in resolving various situations, such as hostage standoffs or apprehensions of dangerous subjects.An expansion to SWAT 4, entitled SWAT 4: The Stetchkov Syndicate, was released on February 28, 2006.