Invincibility
Press [Left], [Up], [Right], [Up],
[Left]x2, [Up], [Right], [Up], [Left],
[Up], [Left], [Start] at the title screen.
Seven extra tanks
Press [Left], [Up], [Right], [Up],
[Left]x2, [Up], [Right], [Up], [Left],
[Up], [Right], [Start] at the title screen.