5
Basic Play
Junior's purpose: to steal the key from Mario and free Donkey Kong.

Gather the keys on screens 1 through 3, then take them all to screen 4 and put them in the keyhole at the top of the screen to open the cage. If you're hit by an enemy or if you fall from a chain or vine, you'll get no bonus, and Donkey Kong Jr. will lose a life. If Donkey Kong Jr. loses all his lives, the game is over.