The Adventures of Cookie & Cream: Part 14: Music World 4 (Puzzle Piece)
4Among other things, that big creature from Stage 3 of this world is back. Instead of using a loud noise to stun it, you have Cream play a music box, making a lullaby that puts the creature to sleep so that Cookie can safely move past it.
The biggest highlight of this stage is the huge keyboard that you see past the huge violin. Have Cookie press the blue button on it and listen to the 3 keys that automatically get played. Use both Cookie and Cream to play the right 3 notes in the right order on the piano, so that they will lower the golden platforms that will help you continue to the end of the stage.
This took me quite a while, because this "Simon Says" game of music is randomized every time you press the blue button. If you screw up one sequence, you'll have to start over and play a different sequence correctly. At the very least, you will only have to have the rabbits step on the white keys to play this out.
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At the end, after jumping on giant maracas, Cookie & Cream clap a cymbal together to open the gate to a theater, where the Music World's boss is located!