In Size Squared, there is a base green square and a red square that grows in the middle. You must tap on the screen when the red square is approximately the same size as the green square to score points. There are four different modes of play: easy, hard, harder, and hardest. In each mode, you have 3 lives. If the red square grows a little bigger than the green square, you lose a life. A life is also lost if you tap too early. Each mode adds elements to the basic concept to really amp up the difficulty.