While at the title screen, hit U - U - D - D - L - L - R - R, if done correctly the announcer will say "outstanding". Press start to enter the main menu. While at the menu screen, highlight the options selection and press the two top trigger buttons (L and R).

** this code must be done in order to access the secret characters

001-001: Unlimited Run
002-002: All Time Weapons
010-010: Disable Max Damage
012-012: Noob Saibot Mode
020-020: Red Rain
050-050: Explosive Kombat
100-100: Disable Throws
110-110: No Throws & Max Damage
111-111: Free Weapon
123-123: No Power
222-222: Random Weapon
321-321: Big Heads
444-444: Armed & Dangerous
555-555: Many Weapons
666-666: Silent Kombat

011-011: Goro's Lair
022-022: The Well
033-033: The Elder Gods
044-044: The Tomb
055-055: Wind World
066-066: Reptile's Lair
101-101: Shaolin Temple
202-202: Living Forest
303-303: The Prison
313-313: Snow Stage
323-323: Church Stage
343-343: The Netherealm
353-353: Soul Chamber
363-363: Ladder Stage

CODE 01 - Free Weapon - 6
CODE 02 - Throwing Disabled - 2
CODE 03 - Armed & Dangerous - 8
CODE 04 - Silent Kombat - 10
CODE 05 - Explosive Kombat - 11
CODE 06 - Random Weapons - 7
CODE 07 - No Power - 12
CODE 08 - Many Weapons - 9
CODE 09 - ?
CODE 10 - ?
CODE 11 - Weapon Kombat - 14
CODE 12 - ?
CODE 13 - Noob Saibot Mode - 15
CODE 14 - Red Rain - 16
CODE 15 - Maximum Damage Disabled - 3
CODE 16 - Throwing & Maximum Damage Disabled - 4
CODE 17 - Stage: Goro's Lair - 17
CODE 18 - Stage: The Well - 18
CODE 19 - Stage: Elder Gods - 19
CODE 20 - Stage: The Tomb - 20
CODE 21 - Stage: Wind World - 21
CODE 22 - Stage: Reptile's Lair - 22
CODE 23 - Stage: Shoalin Temple - 23
CODE 24 - Stage: Living Forest - 24
CODE 25 - Stage: The Prision - 25
CODE 26 - Unlimited Run - 5
CODE 27 - Stage: The Ice Pit - 26
CODE 28 - Stage: Church - 27
CODE 29 - Stage: Netherealm - 28
CODE 30 - Stage: Soul Chamber - 29
CODE 31 - Stage: Ladder - 30
CODE 32 - ?
CODE 33 - Big Head Mode - 1