At the main menu, hold L2 and press Square, Up, Down, Right, Left, R2, Square to unlock the classic Mortal Kombat 2 arcade game in the Kontent menu. If you entered the code correctly, you will hear a sound. Alternately, successfully complete all five Smoke missions. Note: This feature is not available in the European version of the game.
Play as Scorpion
At the main menu, hold L2 then press Square, Up, L1, R1, Left, Right, Square to unlock Scorpion in Single Player, Co-Op, and Versus modes. If you entered the code correctly, you will hear a sound. Alternately, successfully complete the game with Liu Kang to unlock Scorpion in Single Player and Co-Op mode. To unlock Scorpion in Versus mode, in the Foundry area, follow the pathway downstairs to the left of the save point. Two archers will break through the wall. Throw one at the wall to the left of the doorway to break it open, giving you access to a hidden room full of lava and a Ying Yang on a ledge. Grab one of the archers and throw him into the lava. Then, double jump off his back to get the Ying Yang that unlocks Scorpion in Versus mode.
Play as Sub-Zero
At the main menu, hold L2 then press Square, Down, Up, L1(2), Up, Square to unlock Sub-Zero in Single Player, Co-Op, and Versus modes. If you entered the code correctly, you will hear a sound. Alternately, successfully complete the game with Kung Lao to unlock Sub-Zero in Single Player and Co-Op mode. To unlock Sub-Zero in Versus mode, take the boat ride across blood lake. You can find Sub-Zero's Versus mode icon in back of the lion-like statue to your left (when facing the big door). Run along the wall and double jump at the end to collect it.
Play as Baraka
In the Soul Tomb Portal, go to the area where you must wall climb. You will see a path that leads to the left and one that leads to the right; take the path to the right. There will be a statue on the path; use the Fist of Ruin to break it. Continue along the path and use the long jump ability to cross the gap and get the Koin to unlock Baraka in Versus mode.
Play as Johnny Cage
Get to the area in the Wu-Shi Academy where everything is burning. Go to the extreme right of the gate, then jump onto the roof of the house. Run to the right and jump to reach a new platform with a boulder blocking your way. Collect the Koin to unlock Johnny Cage in Versus mode.
Play as Kitana
In the Mortal Kombat 2 arena level (just before the portal with the two statues in front of it) in the Evil Monastery, you will find a number of pillars. Jump on the half broken pillar, then double jump on the roof. Collect the Koin to unlock Kitana in Versus mode.
Play as Noob Saibot
Have a match in Versus mode with Sub-Zero vs. Sub-Zero. Player one will be Sub-Zero, and player two will be Sub-Zero's brother, Noob Saibot.
Play as Reptile
Go to the section after the Brotherhood Of Shadow in Living Forest. Long Jump across the gap with the small waterfall, then go through the door. Get the clay statues to come to life, then destroy their shield. Get one of them near the giant stone column on the other side of the stream, near where you entered. Throw the clay statue into it and it will fall. Return to where the little waterfall was located and get the Koin to unlock Reptile in Versus mode.
Easy health
If you use a save point, your health will be fully restored, even if you do not save.
Easy experience
It is possible to get all the experience needed to get all the moves at the beginning of the game. After you fight your way through the start and cross the first pit, you will be in a room with a lamp hanging from the ceiling. In the next room, you will first see a quick intermission sequence of the Oni killing one of their own. Afterwards, you must fight them. Raiden will tell you to throw one of the enemies through the wall to progress. Do not break the wall. Instead, keep killing the Onis, which will keep appearing. Try to get a high combo score to get more points. If your combos are high and you perform a fatality, you will get a little bonus experience. To speed up the process, pay attention to the top left where your combo count is displayed. If at anytime you see "Toasty", instead of "Impressive", "Outstanding", etc., press Start to get an extra 1,000 experience points. Keep repeating this to master all your moves very fast.
About half way through the Wu Shi Academy, you will have to get a weapon to cut the ropes to three cauldrons. Johnny Cage will be fighting with you and three Tarkatans will appear. The Tarkatans will keep respawning until the ropes to the three cauldrons are cut. Keep killing the Tarkatans to get an unlimited amount of experience. You can also keep killing the Tarkatans with either of the two weapons that you can pick up, and once the weapon disappears, it will respawn again at the same location.
When you reach a multiple of 10 in your combo meter, the announcer will say comments like "Outstanding!", "Superb!", etc.; however, the word "Toasty!" will be spoken at random times. When "Toasty!" is spoken, press Down + Start to get an extra 1,000 experience points. If done correctly, the screen will flash and "TOASTY! 1000 Pts." will be displayed.