Sonic Spinball (Game Gear)
This game has a prototype article
Hidden developer messages.
Diet Sonic Spinball.
Play sound effects 0, 2, 1, 5, 6, 6 in the Sound Test, then pause during gameplay and press Down.
In the Options menu, play sound effects 0, 9, 0, 1, 6, 8 in the Sound Test (the screen will shake to confirm), then pause during gameplay and press 2.
Present at 0x4C61:
1994-05-30 P.M. FINAL REV. 20 (K)
It can be displayed in the Options menu by playing sound effects 0, 5, 0, 3, 6, 0 in the Sound Test.