Tap Tap is a series of rhythm games by Tapulous available for the iOS of which several versions, both purchasable and free, have been produced. The goal of the game is to tap each of the colored balls when they reach a line at the bottom of the screen. If the ball is hit on the beat, the player gains points, but if not, it counts as a miss. If a player taps the screen without a tapper on the beat, the streak will go back to 0 and a few points will be lost except for 16x. There are also 'shakes', which require the player to move the iPhone, iPod touch or iPad to the right, left, or backwards. The franchise has combined sales of over thirty-five million as of September 2009, making it one of the best-selling video game franchises of all time.