Samurai Warriors (戦国無双:Sengoku Musou in Japan ) is the first title in the series of vieo games created by Koei's Omega Force team based loosely around the Sengoku ("Warring States") period of Japanese history and is a spinoff of the Dynasty Warriors series. A port of this game called Samurai Warriors: State of War has been released for the PlayStation Portable, which includes additional multiplayer features.