sentences: "Guitar Hero World Tour", previously named "Guitar Hero IV", is the fourth full game in the series and was released on October 26, 2008 for PlayStation 2, PlayStation 3, Xbox 360, and Wii.Analysts had expected that future "Guitar Hero" games in 2008 would include additional instrument peripherals to compete against "Rock Band"; "Guitar Hero World Tour" was confirmed as in development following the announcement of the merger between Activision and Vivendi Games in December 2007.