Ballz!

At the Title screen, press A, A, Down, C, B, A, Up, Up, Down.

At the title screen press A nine times to enable Hyper Mode (2-players only.)

This code is for 1 player mode. In title screen, press C C C B B B A A A C A B. If you want his body to be sea green, press up. If you want his horn to be red, blue, green or black, press down.