Bonus Characters
The PSP version of "Mortal Kombat: Unchained" allows you to fight with alternative characters once certain characters have been unlocked as you advance through the game. If you unlock Koffin QT, you can fight as a Seido Warrior by selecting a character known as Hotaru and pressing "Start" at the same time. If you unlock Koffin SR, you can fight as a Tarkatan Warrior by selecting a character known as Baraka and pressing "Start" at the same time. If you unlock Koffin PD, you can fight as a Shokan Warrior by selecting a character known as Goro and pressing "Start" at the same time.
Scorpion vs. Scorpion
During the main menu of the game, venture to the Krypt and unlock the tomb that has the alternate costume for Scorpion, which will cost you 1,500 coins. Accumulate coins by playing through the game. Once the costume has been unlocked, go to the practice mode. Select Scorpion as a character and press the "Start" button. Have a second player also choose Scorpion, but instead of pressing "Start," have her press the "X" button. If done correctly, one player will be Scorpion from "Unchained," while the other will be Scorpion from "Mortal Kombat 4."
Concept Art
Less of a cheat and more of a perk, you can unlock concept art revealing Mileena in a "sexy" costume. Venture to the main menu of the game and then go to the Krypt. Locate a gravestone marked with the letters "GT." You can unlock the coffin inside for 217 Sapphire Koins. Once unlocked, you can gaze upon a piece of art showcasing Mileena in all her glory. In the piece, Mileena is holding two blades and sporting a pink veil, pink boots and a pink top and bottom.
All Costumes
As you fight your way through "Mortal Kombat: Unchained" you will begin to unlock different costumes for the various fighters. However, this can become quite time consuming, not to mention drain your PSP's battery. Instead, go to the game's main menu. Press Up, Down, Up, Down, Square and Square. You will hear a chime. When you select a character, all of her costumes will be unlocked.