Have you ever thrown a ball in the air and caught it? Then you understand the rules of this simple game. Simply throw the ball in the air, catch it, and throw it again. You lose if it touches the ground. The more times you catch the ball, the higher you can throw it.
The catch? Sometimes, random "actions" will occur when you catch it. Whatever actions can happen depends on what "theme" you have set. "Themes" can alter the color scheme of the game, and can be unlocked or bought as an In-App Purchase.
If youre good enough to unlock a theme, you can also unlock differently colored balls to play with.
Good luck, and have fun!