Mortal Kombat II

When the opening credits appear, type "AICULEDSSUL". If you did it right, a tone will sound. When the Acclaim logo appears, press F9 for a special menu.

To fight Jade, work your way to the match before the mystery fight (the one titled "?"). During this battle, defeat your opponent using nothing but low kicks. If you manage this feat you'll fight Jade in the next battle.

To fight Noob Saibot, get 50 wins in a row.

To fight Smoke, press DOWN + START on the Bridge stage when Dan says "Toasty!"