Sonic Mega Collection Plus Cheats

Debug Mode
To enter Debug Mode, play these sounds from the level select screen: 1, 9, 9, 2, 1, 1, 2, 4. Press [Start] and hold [A]. To start debugging press [B], then you can select any sprite in that level and put it on the screen. To select a different sprite press [A], and to place it on the screen press [C]. Note that sprite selection is different from Zone to Zone. Also, instead of displaying the time elapsed, it displays the number of sprites currently on the screen.

Level Select
From the main screen, select Options. Select Sound Select and play sounds 19, 65, 9, 17, then push [C]. Press [Start] to return to the main screen, and when Sonic and Tails appear hold [A] and press [Start].

Alternate Ooze and Comix Zone
The Ooze: Unlock all games with exception to Ristar.
Comix Zone: Scroll down the list of Genesis-only games (including unlockables) and play them each 20x.

Unlock Games
Blue Sphere game - Play Sonic the Hedgehog and Sonic 3D Blast 20 times each, exit to the title screen and then go back into the game select screen and Blue Sphere will now be unlocked.
Flicky - Play Mean Bean Machine 30 times and Flicky will be unlocked.
The Ooze - Have a Sonic Heroes save on the Xbox.
Comix Zone - Have a Sonic Heroes save on the Xbox.