This is the PC version! Next cheapest is £17.73 @ TheHut
To see the reduced price you must use the GFWL client (it's like Steam) and browse the store that way. Go here to download the client...http://www.microsoft.com/games/en-us/live/pages/livejoin.aspx
Street Fighter IV brings the legendary fighting series back to its roots by taking the beloved fighting moves and techniques of the original Street Fighter II and infusing them with Capcom's latest advancements in next generation technology to create a truly extraordinary experience. Everything that made the legendary Street Fighter II a hit in the arcades, living rooms and dormitories across the globe has been brought back in Street Fighter IV. Players will be able to play their favorite classic characters, such as Ryu, Ken, Chun-Li and Guile, along with new characters, including Crimson Viper, Abel, El Fuerte, and Rufus. Characters and environments are rendered in stylized 3-D, while the game is played in the classic Street Fighter 2-D perspective with additional 3-D camera flourishes. Six-button controls for the game return, with a host of new special moves and features integrated into the gameplay system. Street Fighter IV brings a brand new fighting game to fans the world over.