Play a Challenge game and get a high score then submit your initials as one of the following codes to unlock the corresponding effect.

Unlock ALL Cheats:
9AC

Unlock ALL Kits:
7UK

Unlock ALL Players:
6UP

Unlock ALL Stadiums:
8US

Unlock Big Heads/DK Mode:
1BH

Unlock Crazy mode:
5CM

Equalize Stats:
3ES

Time of Day:
2TD

Unlock Unlimited Special Shots:
4IS