Sonic Classic Collection
Debug Mode for Sonic 1.
At the title screen, press [A] twice, then [Up], [Down], [Left] and [Right].
You should hear a ring chime. Hold down [Y] and press [Start].
Debug Mode is now active, as indicated by the score tally being made of letters and numbers.
[Y] & [C] are still jump while [B] changes Sonic into an object which you can spawn by pressing
the [C] button. Press [Y] to cycle through them and [B] to change back to normal.
Be warned that over-using this will cause temporary slow-down and could cause problems.
Debug Mode
[A], [A], [Up], [Down], [Left], [Right]. Hold [Y] and Press [Start]
Sonic The Hedgehog Level Select:
At the title screen press up down left right.
If done correctly you should hear a ring sound.
Now hold Y and press start. You can now choose
any stage you want.
Level select in Knuckles in Sonic 2:
Press [up] [up] [down] [down] [left] [right] [left] [right], then hold [Y] and press [start].