Secret menu:
Press B, A, Down, Left, A, Down, C, Right, Up, Down at the main menu. An option for a "Secrets" menu with timer, ending story, and starting level selections will appear.

Killer codes mode:
Press C, Right, A, Left, A, Up, C, Right, A, Left, A, Up at the main menu,. A new menu option with quick finishing move, fight as Smoke, fight as Bosses, and Galaxian mini-game options will appear.

Endurance mode:
Highlight the "Start Game" option on the main menu. Hold A + B + C and press Start. Press Start, then press Left and Right to choose a character for each box or press B to choose a random character for the current box. Hold Up and press Start to for all random characters.

Fight as Smoke:
Press A, B(2), A, Down, A, B(2), A, Down, Up(2) after the bell rings at the Mortal Kombat 3 logo.

Fight against Smoke:
Press A(2), C(3) on controllers one and two at the versus mode screen. The winner of the first round will fight Smoke.

Random fighter:
Hold Up and press Start at the character selection screen.

Secret stage:
Defeat Shao Kahn to display a message stating that you are the new MK3 champion. Press Start on the controller that was not used to defeat Shao Kahn. The two player selection screen will appear with "-" displayed as the next level. Continue game play to fight on the screen that states you are the next champion. Note: Using an uppercut during this match will result in the fight ending with no winners. Defeat your opponent without using any uppercuts to fight Shao Kahn again.

Always defeated with fatality or brutality:
Lose a single player match and hold Down on controllers one and two. Your opponent will end the match with a fatality or brutality.

More bonus game lives:
Note: A six-button controller is required for this code. Hold X + A + B + C + Z + Y at the "Galaxy" screen.

Advance through matches:
Begin game play in single player mode. Press Start on controller two and defeat your opponent to easily advance through the match.

Kombat Kodes:
Select a two player game and enter the Vs. screen. Use the controller one buttons to select the first three characters of the Kode, and those same buttons on controller two for the last three characters. Enter a valid Kode before the Vs. screen fades. Pressing a button will cycle the specific character to which it is assigned: