Select game 13 and allow the incoming missiles to reach your cities, and fire all your missiles without scoring any points. The city on the right side will turn into "RF", the initials of programmer Rob Fulop.
Aim and fire three missiles at the highest part of the screen when game play first begins. Press Reset before the missiles explode. The missiles will remain in view and a varying number points will be added to your score after they explode.
Missiles on game selection screen
Start a new game and start pressing Select while some missiles are shooting down. The missiles will keep flying as you cycle through the game variations.
When the game first begins, fire three missiles at the top part of the screen (the highest the cursor will go).
Then, RESET the game before the missiles explode.
You'll still see the missiles, and when they explode you may get some free points.
Sometimes it takes a few tries, but once in a great while you get a jackpot of points
(I think my highest cheat was around 1200 points on a Level 1 game).
Keep hitting the fire button to shoot up to 8 missiles.
Game Shark Codes
*NoteL You must have a 2.1 or higher version of the Game Shark. Only Game Boy Color.
Infinite Missiles Left Side
Infinite Missiles Right Side
Select game 13. Let missiles rain on all your cities and waste all your missiles without scoring any points.
The rubble of the rightmost city will change to "RF", the programmer's initials (Rob Fulop)