To perform the Level Select Code, Press Up, Down, Left, and Right. You'll hear a Ring sound, which confirms that you completed the code. Hold A (Depending on how you set the controls for the game) and Press Start. You will have access to the level select, as well as the Special Stage, Final Zone and Sound Tests.

Most of the Sonic the Hedgehog 2 Codes that you can unlock/perform. These are the well known codes.

The codes in the game allow you to gain invincility, Infinite Shurikens, and Bonus Points.

Enter all codes at the Title Screen

First hit select and go to "Control Setup". Now make sure the game is in ABC Mode.
At the title screen highlight "Options". Now press & hold A+B+C. In the options screen continue holding A, release only B & C. Configure the game however you like. Now only press the B button to confirm all choices until you have selected your character. (don't forget to continue holding A the entire time) Once you have selected your character a number should appear on screen allowing you to select your level.

First hit select and go to "Control Setup". Now make sure the game is in ABC Mode.
At the title screen highlight "Options". Now press & hold A+B+C. In the options screen continue holding B & C, release only A. Configure the game however you like. Now only press the Start button to confirm all choices until you reach the character select screen. (don't forget to continue holding B & C the entire time) If you look in the lower right hand corner of the character select screen the Credits should now say 8 instead of 3.

First hit select and go to "Control Setup". Now make sure the game is in ABC Mode.
At the title screen highlight "Arcade". Now press and hold Down/Left + B. Continue holding the buttons at the character select screen, and press Start. A number should appear in the upper left hand corner of the screen. Press up or down to select your level.

Player One:
When selecting a character, make sure your cursor is on Akira. Press left to go to Jacky, then press right to go back to Akira. When repeating this process, you'll hear a countdown begining at 5. Keep going till you reach zero. Once you reach zero, Dural will now be playable.

Player Two:
When selecting a character, make sure your cursor is on Jacky. Press right to go to Akira, then press left to go back to Jacky. When repeating this process, you'll hear a countdown begining at 5. Keep going till you reach zero. Once you reach zero, Dural will now be playable.

Press A, B, C, B on the Options Screen. You will be taken to a level select screen.

First hit select, go to "Control Setup" and make sure the game is in ABC Mode. Enter the options screen press A, B, B, A, Down, A, B, B, A. This will bring you to the Debug menu.

First hit select, go to "Control Setup" and make sure the game is in ABC Mode. Pause the game and press A, B, Right, A, C, A , Down, A, B, Right, A (ABRACADABRA). Unpause and your life will be restored.

First hit select, go to "Control Setup" and make sure the game is in ABC Mode. Pause the game and press Right, Up, B, A, Down, Up, B, Down, Up, B. Unpause and you will have 1 extra life. You can keep doing the code for as many lives as you like.

First hit select, go to "Control Setup" and make sure the game is in ABC Mode. Pause the game and press Up, Right, A, B, A, Down, Left, A, Down. Unpause and you will be brought to the level select screen.

First hit select, go to "Control Setup" and make sure the game is in ABC Mode. Pause the game and press B, A, B, A, Left, Up, Up. Unpause and your energy will be fully restored.

First hit select, go to "Control Setup" and make sure the game is in ABC Mode. Pause the game and press C, A, Left, Left, Down, A, Down. Unpause and you will have a new weapon. You can keep entering the code until you get the weapon you desire.

Press the Select Button and go to Control Setup. Enable ABC Mode.

When the level name appears, Hold Square + Start Button until the level begins.
When the game screen appears, unpause and you will be invincible.

Note: It will still show that you take damage, but you will still be alive even if your energy bar is fully depleted.

Press the Select Button and go to Control Setup. Enable ABC Mode.

On the "Make your Move" screen after the Title Screen, Hold Up + Square + Circle and Press the Start Button. Release the buttons when a "Round 1" screen appears, then press Up or Down to choose your starting round.

Press the Select Button and go to Control Setup. Enable ABC Mode.

At the character select screen, choose your character and enter the code.

Enter the following at the title screen:

Enter the Juke box and select the following with the circle button.

Enter these codes at the password screen in Options

To unlock this classic arcade shooter, go play sonic the hedgehog and collect one chaos emerald.

To collect a chaos emerald, you have to collect 50 rings during the course of a stage and then jump through the giant ring at the end. Once inside, you'll be able to collect the emerald and unlock this classic!

To unlock the sound test, beat the game. Then, at the title screen, press B (or whatever button you have mapped as B). A menu will pop up, and you can listen to all the music in the game.

To unlock Sega's arcade game Tac-Scan, make it to the bonus stage in the first level of Ristar.

Bonus arcade games needed to be unlocked in order to unlock the arcade version of Altered Beast.

At the title screen:

First hit select and go to "Control Setup". Now make sure the game is in ABC Mode. At the title screen highlight "Options". Now press & hold A+B+C. In the options screen continue holding A, release only B & C. Configure the game however you like. Now only press the B button to confirm all choices until you have selected your character. (don't forget to continue holding A the entire time) Once you have selected your character a number should appear on screen allowing you to select your level.

First hit select and go to "Control Setup". Now make sure the game is in ABC Mode. At the title screen highlight "Options". Now press & hold A+B+C. In the options screen continue holding B & C, release only A. Configure the game however you like. Now only press the Start button to confirm all choices until you reach the character select screen. (don't forget to continue holding B & C the entire time) If you look in the lower right hand corner of the character select screen the Credits should now say 8 instead of 3.

First hit select and go to "Control Setup". Now make sure the game is in ABC Mode.
At the title screen highlight "Arcade". Now press and hold Down/Left + B. Continue holding the buttons at the character select screen, and press Start. A number should appear in the upper left hand corner of the screen. Press up or down to select your level.

First hit select and go to "Control Setup". Now make sure the game is in ABC Mode. Now enter the options screen and press A, C, B, C.

First hit select, go to "Control Setup" and make sure the game is in ABC Mode. Enter the options screen press A, B, B, A, Down, A, B, B, A. This will bring you to the Debug menu.

First hit select, go to "Control Setup" and make sure the game is in ABC Mode. Pause the game and press A, B, Right, A, C, A , Down, A, B, Right, A (ABRACADABRA). Unpause and your life will be restored.

First hit select, go to "Control Setup" and make sure the game is in ABC Mode. Pause the game and press Right, Up, B, A, Down, Up, B, Down, Up, B. Unpause and you will have 1 extra life. You can keep doing the code for as many lives as you like.

First hit select, go to "Control Setup" and make sure the game is in ABC Mode. Pause the game and press Up, Right, A, B, A, Down, Left, A, Down. Unpause and you will be brought to the level select screen.

First hit select, go to "Control Setup" and make sure the game is in ABC Mode. Pause the game and press B, A, B, A, Left, Up, Up. Unpause and your energy will be fully restored.

First hit select, go to "Control Setup" and make sure the game is in ABC Mode. Pause the game and press C, A, Left, Left, Down, A, Down. Unpause and you will have a new weapon. You can keep entering the code until you get the weapon you desire.

Go to jukebox from the main menu and select these numbers in the following order:

During gameplay, make sure the controls are in ABC mode and pause the game. Press O, square, left, left, square, O, square, X (C-A-L-L-A-C-A-B). When you unpause, Vectorman will be replaced with a crosshair. You can move the crosshair anywhere in the level, and moving it over an enemy will damage them. Does not damage bosses, and you can't collect powerups. Repeat the code to return to normal.

Invincibility
On the Options Screen, highlight the "MUSIC" sound test and play these songs in order: "He Runs", "Japonesque", "Shinobi Walk", "Sakura", and "Getufu". Exit the Options Screen and start the game, you will be invincible.

Unlimited Shurikens
On the Options Screen, set "SHURIKENS" to 00, then set "S.E" sound test to "Shuriken". Highlight "SHURIKENS" again and the 00 will change into an infinity symbol.

Enter "PLEASE__" where "__" is replaced by the two letters of the level you want to go to.

Start a new game after entering the code to play through with unlimited air.

First enable ABC mode in Controller Setup. There are two sound test areas, one in options and the other in Level Select Screen. All of the follow passwords work only in the level select sound test, except the password to enable level select.

After getting a game over, go to options menu from title screen. Just hit continue to return to the stage you died in.