Tap the glowing tile before it fades. Speed rises as you score. Misses and wrong taps cost a life. Green tile is a bonus. Purple tile is a slow motion effect. Keep your combo alive for big points.
Keyboard: press the keys 1 to 4 for the top row, Q to R for the second row, A to F for the third row, Z to V for the fourth row. Or use arrow keys to move a cursor with Enter to select.