For a difficulty setting higher than "Hard Rank". During the intro, on controller two press B, B, A, C, U, L, R, D, U, and A. Then press START on controller one. If the code works your score will read "00001" when you start your game.
During the intro, press R, L, A, R, U, C, B, D, L, B, A, U, and START. This allows you to refill your shield at any time during play by pressing A on controller two.
During the intro, press D, D, U, U, R, L, R, L, A, B, and START. There will be a stage-select option on the title screen. Pick a stage and press A to start there. If you pick a number higher than 12, you'll see one of the animated intermissions.
On your last continue, leave the cursor on the words "Continue 01" and wait for the game to go back to the introduction. When the demo sequence begins, press R, U, A, B, C, L, L, D, C, A, and START. You will now have ten continues. This trick can be repeated.
At the title screen, highlight "Option". Press and hold (A+B+C) on controller two and press START on controller one. "Sound Test" will be replaced with "Voice Test". Press L or R to choose a voice, and press A, B, or C to play it. Pressing L or R on controller two alters the speed and pitch of the voices.
At the title screen, press A, B, C, A, B, C, B, C, B, A, and START. Then go to the configuration menu and select the level at which you want to start.
At the title screen, press A, B, C, A, B, C, B, C, B, A, and START. Then begin your game. Now, at any time durring play, (A+B+C) will skip you to the next level.
99 lives and Invincibility:
At the title screen, press A, B, C, A, B, C, B, C, B, A, and START. Move the cursor to options in the configuration menu. Then hold R while pressing A several times. Eventually, the word "MY99" will appear on the options menu. "MY99" will give you 99 lives. If you continue to press A while holding R, the word "MUTEK1" will appear on the options menu. "MUTEK1" will make your ship invincible.
Sonic CD (SegaCD)
At the title screen, press D, D, L, R, and A.
At the title screen, press D, D, L, R, and A. Change the sound settings to "FM NO. 40", "PCM NO. 12", "DA NO. 11", and press START. Then press START again. During the game, you can now change Sonic into different objects and even other characters.
When the title screen appears, press U, D, D, L, R, and B. A stage select screen will appear.
ARBOGAST - Sandman Zone MECHANIC - Lizard Zone
REACTORS - Electro Zone PERMANENT - Vulture Zone
PUBLIC45 - Hobgoblin Zone KIDNEY2 - Venom Zone
NORBLE - Mysterio Zone PENCIL6 - Kingpin Zone
Streets of Rage (SegaCD)
Level and life Select:
At the title screen, highlight "Options", and while holding (A+B+C+R) on controller two, press START on controller one.