Enter the following case-sensitive codes at the 'Cheat' screen:

ABILITYBONUS Better players BALLHEAD Basketball heads BEFOREIMAGE Show ball trails BIGFOOT Big feet BIGHAND Big hands BIGHEAD Big heads DARKNESS No lighting DUNKERS Easy dunks EXCELLENT Better shooting INVISIBLE Invisible players MINIMINI Small players NOSPECTATOR No spectators PANCAKE Flat players

Thanks to Revolution reader Vibofax!