Click the Green Flag to start. The game is similar to pong if you had no friends. The objective is to keep the moon from leaving the universe by moving the earths to bounce it back into the middle. There are six modes, three are the basic difficulties Easy, Medium, and Hard. Then there is a custom mode where you can pick the settings. The other two are challenge modes. They are infinite, where there is no end and the moon's balance must be constantly checked until it eventually leaves the universe, and Survival where instead of the moon you must keep other planets from leaving our universe.