Fans of Nintendo's mobile racing game can play it on the iPhone, iPad and iPod Touch. Android devices also now carry 'Mario Kart Tour,' which is free to play. Purchases will be available within the game that are used for upgrades. You must also pay to unlock certain features. Through online rankings, players of 'Mario Kart' will be able to view each other's results worldwide. Every two weeks, Nintendo will also cycle its "global tour" section of the game. Courses will feature aspects of real-life cities and levels from previous games.