Warriors Orochi (無双オロチ Musō Orochi) is a beat 'em up video game for PlayStation 2 and Xbox 360, developed by Koei and Omega Force. It is a crossover of two of Koei's popular video game series, Dynasty Warriors and Samurai Warriors (specifically Dynasty Warriors 5 and Samurai Warriors 2) and the first title in the Warriors Orochi series. The game was released on March 21, 2007 in Japan, September 18 in the United States, September 21 in Europe, September 27 in Australia and September 28 in New Zealand. The game came out for the Xbox 360 in Japan on September 13, and the UK version came out on the same date as the PlayStation 2 version in the United States. The game was ported to the PlayStation Portable, released in Japan on February 2008, March 25 in the US, and March 28 in the UK. A PC version was released in the US on March 25, 2008.