Mortal Kombat

10 credits:
In the Japanese version, press Left, Up, Right, Up, Left, Up when Goro appears at the Acclaim logo. A sound will confirm correct code entry. The game will now start with 10 instead of 4 credits.

Fight as Goro:
Successfully complete the game. When "The End" message appears, quickly hold Up/Left + Select + A until the title screen appears. Press Start to began a new game.
Information in this section was contributed by Powerbomb14.

Fight as Reptile:
Select any character and defeat Shang Tsung. When he releases all the fighters souls, hold L + R when Sub-Zero appears. Keep holding L + R until the title screen appears. Start a new game. At the fighter selection screen, Reptile's face will be at the top middle of the fighter selection screen.
Information in this section was contributed by Joe Matera.

Fight against Reptile:
Play the game until reaching the Pit. Achieve a double Flawless victory without blocks and perform a fatality to end the match.
Information in this section was contributed by Imayoda235.

Alternate introduction sequence:
Hold L + R before the Acclaim logo appears. Continue holding the buttons until it disappears..

Hint: Move players off the screen:
Start a two player tournament battle with any of the fighters. Fight until one of the characters is one throw away from defeat. Allow the time run down until one second is remaining. Finish off the fighter with a throw (stand next to the opponent and press B). In the next round, either character may be moved off the edge of the screen.
Information in this section was contributed by Jesse Smith.

Hint: Motionless opponent:
Start a one player match with any fighter (Cage or Liu Kang work the best). Repeatedly jump over your opponent and kick without hitting him. Continue doing this until the CPU blocks. Then, jump back over your opponent once more time, without kicking. After landing, wait and do not press any buttons. The CPU opponent will remain motionless until hit.
Information in this section was contributed by Jesse Smith.

Hint: Leave opponent standing:
Use Sub-Zero to defeat an opponent in the first round. During the second round, run your opponent's power meter all the way down without the "Finish Him" appearing on the screen. Use the Freeze move to ice the opponent until "Finish Him" flashes. Then, execute the finishing move. Sub-Zero will shatter the ice but leave the opponent standing.
Information in this section was contributed by Jesse Smith.

Hint: Easy special:
This trick allows you to perform any special move that ends with pushing an attack button by pressing only that button at the beginning of the second or third round. Finish your opponent in round one (or two) by using a special move. When the next round begins you can continue to use that same special move by only pressing the final attack button as long as you do not press any other buttons or move the fighter using the D-pad. For example, use Liu Kang's fireball to defeat the opponent in round one. At the beginning of round two, you can repeatedly throw fireballs by pressing only HP.
Information in this section was contributed by Jeff Behnke.

Hint: Johnny Cage: Fatality:
Stand next to your opponent and press Forward, Forward, Forward, Y. Johnny will kick through the opponent.
Information in this section was contributed by Shaun Mortenson.

Hint: Johnny Cage: Special move:
Wait until "Finish Him" appears. Stand close to your opponent, then press L + R + B at the same time to get a surprise. Note: Make sure the opponent is not Sonya.
Information in this section was contributed by Joe Matera.

Hint: Kano: Fatality:
Stand next to your opponent and press Back, Down, Forward, B. Kano will rip out his opponent's heart.
Information in this section was contributed by Shaun Mortenson.

Hint: Liu Kang:
Stand anywhere and hold Block, then rotate the D-pad in a full circle towards your opponent. Liu will do an uppercut.
Information in this section was contributed by Terry Jeralds and Shaun Mortenson.

Hint: Raiden: Fatality:
Stand next to your opponent and press Forward, Forward, Back, Back, Back, Y. Raiden will electrocute the opponent.
Information in this section was contributed by Shaun Mortenson.

Hint: Scorpion: Fatality:
Stand about three characters spaces away and hold Block, then press Up, Up. He will then burn his opponent.
Information in this section was contributed by MAZTERDJ2000 and Shaun Mortenson.

Hint: Scorpion: Easy victory:
Select Scorpion and keep repeating his "Harpoon" move.
Information in this section was contributed by Dillon Schea.

Hint: Sonya: Purple Rings:
To do Sonya's purple rings press Away(2), B.
Information in this section was contributed by Craig Darwen.

Hint: Sub-Zero: Fatality:
Stand four character spaces apart and press Forward, Down, Forward, Y. Sub-Zero will freeze the opponent and break him to pieces.
Information in this section was contributed by Shaun Mortenson and Smokeyvapors20.

Hint: Keep punching after victory:
When "Finish Him" appears, punch your victim down. When he or she goes down, keep pressing B. Your character will still be punching.
Information in this section was contributed by Joe Matera.

Hint: Star Fox reference:
In the courtyard, the statues behind the fighters will be Fox McCloud with his pistol.
Information in this section was contributed by Joe Matera.

Glitch: Night fighting:
Two players are required for this trick to work. First, choose any two characters. Then, start a match against one another. Each character, first one player then the other, should perform a flying jump kick (Up/Toward + Kick). After performing one of these each, back away and let the time run out. It should be counted a draw. In the next match, do the same thing, letting the time run out. In the third and final match, one character must get a flawless victory. At the end of this round, regardless of the fact that no one has a win, the game will prompt for a "Finish Him". Do your fatality or whatever. Then, whoever lost the match when prompted to continue, should press Start. The match will restart with the same characters, but the screen will be dark as if going for a fatality.
Information in this section was contributed by Scott Streets.

Glitch: Frozen Reptile:
Play against the CPU or another human player. Have both players be Sub-Zero. Have the lighter Sub-Zero (player one) freeze the darker Sub-Zero (player two). Notice that Sub-Zero is wearing green, and it looks like Reptile has been frozen.
Information in this section was contributed by The Runaway Five Teen.

Glitch: Free hit:
Play as Sub-Zero against Goro. If you freeze him when he tries to grab you, he does not actually grab you, but notice your health meter shows unnecessary damage.
Information in this section was contributed by The Runaway Five Teen.