TheGameSite: Gameboy: Go Go Tank
SEVEN CHANCES
On the Title screen, press Left, Up, Right, Up, Left, Left, Up, Right, Up, Left, Up, Right and Start. You'll have seven lives and seven continues.
INVINCIBILITY CODE
On the Title screen, press Left, Up, Right, Up, Left, Left, Up, Right, Up, Left, Up, Left and Start.
