Piano keys will float in front of you, which you should have time to press before they disappear from the screen. With every second, the speed of the keys will increase, and sometimes it can even become a real test, as their speed will be simply stunning. You should only click on the black ones, because if you hit on a different color, the game will end and you will have to start it all over again. The longer the tune you manage to play, the more points you earn.