Cosmo Tank
Books: GAME BOY Secret Codes - Secret Codes 2003 - Game Boy Games Secrets
Get two guns
Sound test
Get two guns
Sent in by Michael Smythe
On the first planet, just before you enter the first cave, there is a large
area. If you wait long enough, giant insects will attack you. Kill theme
to get a power cell. Do this 30 times, and you'll have the 2 best guns in
the game.
Sound test
On the subscreen at the beginning of the Quest Mode, simultaneously
press and hold Down, A and B. While holding these, press Start. If this
is done correctly, the message "Sound Test 01" will appear.