No gravity:
Enter the options menu and select the "SFX" option. Play sounds 0, 9, 0, 1, 6, 8 (in order). The screen will shake to confirm correct code entry. Press 1 + 2 + Start during game play to enable the code.

Skip to Boss level:
Enter the options menu and select the "SFX" option. Play sounds 0, 2, 1, 5, 6, 6 (in order). The screen will shake to confirm correct code entry. Press 1 + 2 + Start during game play to enable the code.

Sonic-Zilla:
Enter the options menu and select the "SFX" option. Play sounds 0, 2, 1, 1, 6, 6 (in order). The screen will shake to confirm correct code entry.

Fast music:
Enter the options menu and select the "SFX" option. Play sounds 0, 4, 2, 5, 5, 7 (in order). The screen will shake to confirm correct code entry. Press 1 + 2 + Start during game play to enable the code.