Click buttons of the same color one after the other! If you manage to clear all buttons on your screen, you may continue with the next round.

Try to clear all same-colored neighbors before continuing with the next color. If you continue too early with a new color, the previously cleared button will be re-activated as a penalty.
But if you cleared more than two buttons of the same color and continue without penalty, you will be rewarded with a white button. This white button is not clickable, but will randomly destroy one of the buttons which have not been cleared at the end of a round.