-Ristar-
Play Blue Sphere, Flicky, Knuckles in Sonic 2 and Sonic 3 and Knuckles 20 times.

-Sonic 3 & Knuckles-
Play Sonic 3 20 times and Sonic & Knuckles 20 times

-The Ooze-
Unlock everything except for Ristar

-Unlock 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.

-Unlock Flicky-
Play Mean Bean Machine at least 30 times to unlock Flicky. You can just enter the game and exit as soon as it loads up. After the 30th time, exit to the title screen and enter the games menu again.

-Unlock Hints-
To unlock the Hints text for each game, keep it open for three hours. You don't have to play the game, just let it run. After three hours, exit out, and when you reenter the game, or check the Hints menu in the Options area, that game's hints will be available.

-Unlock Knuckles in Sonic 2-
Knuckles in Sonic 2 Play Sonic the Hedgehog 2 and Sonic Spinball 20 times each.

-Unlock The Ooze and Comix Zone games-
Have a Sonic Heroes completed game save file on your Xbox hard drive. When you start the Sonic Mega Collection Plus game up, you will have Comix Zone and The Ooze unlocked from the start!!