Battery   Recorder   Matrix  Player 1 Change window four times, each after some time: Next window = 2nd gray button Hints: Change synchronously with Player 2. Make a sign for the change. Player 2 is changing the windows after you like in a canon. Listen to what he makes different while you go into the new window. Try to play something special Player 2 can follow with. After the 4th change, the same windows as in the beginning will be played.