The ninja that you are in control of will constantly keep running from the beginning of the game. All you have to do is protect him. You tap the screen to make him jump over the gaps and save him from falling. The height is decided by how long you hold the screen. A longer tap will make him jump higher, and a shorter one will make him go lower. Why does this matter? Some platforms are higher or lower than the others. Jumping needs to be timed precisely, or you could over jump/under jump; this could result in a "game over".