Our games have at their core a real-time engine that uses your device's system clock to determine everything that happens in the game. Many people like to change the clock to speed up the game, but it will usually cause problems for both the game and the computer at some point. The clock in a computer (and iPhones and iPods are computers) is used by every application and important system function, as well, and it's simply not wise to continually adjust the clock simply to make a game go faster.