Six continues
Hold [Up] + [L] + [R], and press [Start]
at the Konami screen.
Nine continues
Hold [L] + [R] and press [Start]x5
at the title screen.
Unlimited napalm
Walk through the first mission without shooting or
hitting any targets. Your score should be 0 points. Defeat the
Boss without shooting its side gun turrets. Your score should
be 2800 points. When the asteroid level begins, press [X]
to change weapons until the unlimited napalm gun is selected.
Survive this mission to keep the unlimited napalm for the remainder
of the game. Note: It cannot be powered up.
Hints
Failed ending
Go through the first level, and do not destroy the
Boss. Finish the rest of the game to see the failed ending in
which everyone dies.