Figure it out yourself.
Music is by Avicii (main levels), Yolanda B. Cool (alternate end music) and from Toadfanschool's "Color Switch - Climb", Song 6 (for other end music). Note: It is possible to exit the secret level by entering the same code again, but unless you entered it on the last level, it causes some odd musical glitches, so be warned. If you start it up and it starts playing "Best Day Ever", quit the game and restart.
