Make sure you have a save of Sonic Heroes on your memory card (Any save. You dont have to beat the game). After that, play SMC+ and go to the games section. After that, the game will tell you that they are now playable!
Comic Zone - Get a save of Sonic Heroes. play SMC+, go to games, Game is now unlocked.
The Ozze - Get a save of Sonic Heroes. play SMC+, go to games, Game is now unlocked.
Unlocking hidden games
When you initiate Sonic The Hedgehog 1, 2, 3, Sonic And Knuckles, Sonic 3D blast, Dr. Robotnic's Mean Bean Machine, or Sonic Spinball, the screen states that it is logging the game data. That indicates the game is logging in that you have initiated that game once. After initiating a game fifty times, it no longer shows that game-logging screen. It stops the logging sequence screen from ever starting a game again and from then on, just starts the Genesis program itself. To unlock a hidden game, you must start a particular Mega Collection game fifty times, continually exit it, then enter into the game repeatedly. Some hidden games do not necessarily require that you start up fifty times, but you eventually need to do so to unlock all the hidden games.
Blue Spheres: Start Sonic The Hedgehog and Sonic 3D Blast twenty times each.
Comix Zone: Have a saved game file from Sonic Heroes on your memory card.
Flicky: Start Dr. Robotnic's Mean Bean Machine before reaching 50 times. Alternately, have a memory card in slot A with a saved game from another Sega game.
Sonic 3 And Knuckles: Unlocked sometime in the process of starting Sonic 1, Sonic 3, Sonic And Knuckles, and Sonic 3-D Blast fifty times.
Knuckles In Sonic 2: Unlocked in the process of starting Sonic Spinball and Sonic 2 fifty times.
The Ooze: Have a saved game file from Sonic Heroes on the Xbox hard drive. Alternately, this game is unlocked in the process of starting Sonic Spinball and Sonic 2 fifty times.
Ristar: Start the following games fifty times: Sonic The Hedgehog, Sonic The Hedgehog 2, Sonic The Hedgehog 3, Sonic And Knuckles, Sonic 2 And Knuckles, Sonic 3 And Knuckles, Sonic 3-D Blast, Sonic Spinball; and start Blue Spheres 30 to 40 times.
Sonic 3 & Knuckles: Level Select and Debug Mode
Start a "no save" game. In Angel Island Act I, swing on a vine. Press LEFT, LEFT, LEFT, RIGHT, RIGHT, RIGHT, UP, UP, UP.
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.
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.