Guitar Hero III: Legends of Rock is a 2007 rhythm game developed by Neversoft and published by Activision. It is the third main installment and the fourth overall installment in the Guitar Hero series. It is the first game in the series to be developed by Neversoft after Activision's acquisition of RedOctane and MTV Games' purchase of Harmonix, the previous development studio for the series. The game was released worldwide for the PlayStation 2, PlayStation 3, Xbox 360, and Wii in October 2007. Aspyr published the Microsoft Windows and Mac OS X versions of the game, releasing them later in 2007. Guitar Hero III: Legends of Rock retains the basic gameplay from previous games in the Guitar Hero series, in which the player uses a guitar-shaped controller to simulate the playing of lead, bass, and rhythm guitar parts in rock songs by playing in time to scrolling notes on-screen. The game, in addition to existing single-player Career modes, includes a new Co-Op Career mode and competitive challenges that pit the player against in-game characters and other players. Guitar Hero III: Legends of Rock is the first game in the series to include an online multiplayer feature, which is enabled in the PlayStation 3, Wii and Xbox 360 versions. Initially the game offers over 70 songs, most of which are master tracks.[4] The PlayStation 3 and Xbox 360 versions feature the ability to download additional songs. The musicians Tom Morello (of the bands Rage Against the Machine and Audioslave) and Slash (of Guns N' Roses and Velvet Revolver) make appearances both as guitar battle opponents and playable characters in the game. The PlayStation 3, Xbox 360 and Microsoft Windows versions also include Bret Michaels (of Poison) as a non-playable character. Critics and fans acclaimed the game, but reviewers noted a difference in the game's style compared to previous installments, associating it with it being Neversoft's first development attempt with the series. The game is often cited to be too difficult, creating "walls of notes"[5] that are difficult to complete, and led to alterations in note placement for future games in the series. According to Activision, Guitar Hero III: Legends of Rock is the best-selling video game of 2007, both in terms of units sold and revenue earned, and that it is the first single retail video game to exceed one billion dollars in sales. It is one of the best-selling third-party games available for the Wii.