Sent in by Viper-X27
Pause and press Up, Right, Down, Left, Up, Right, Down, Left, Start.
It doesn't work on bosses. The code can be used once per game.
Start the game, then pause it by pressing Start. Press Up, Select, Down,
Select, Left, Select, Right, and Select, then repeat this sequence
two times more. Use this code only for added challenge; it prevents you
from powering up your ship!