Enter MUSIC as a password.
Enter HCBY74+377776 as a password to start as you as far you can in the game in expert mode. Make it through the last stage, defeat Demonyx, and you will not have to go through the game again (as when playing on easy mode).
The Underworld: G5-Y 3133 77774
Final level: ZL14 CB88 CCCCB