The game offers three game modes: a campaign single-player mode (lasting about 6 hours), a "Special Ops" mode for replay value over the campaign where the player or players can collect stars (like in a Mario game), and a multiplayer mode (online and offline). The online mode is why most people play "Call of Duty". The previous "" broke "World of Warcraft"'s record of 11 million people online by 2 million on Xbox 360 alone. "Call of Duty: Modern Warfare 2" managed to sell 1.2 million copies in its first day of release in the UK.