This cartridge offers many variations based around shooting duels.

UFO 1 & 2
The objective of these games is to destroy mmore UFOs than you oppponent. The difference between UFO 1 and 2 is the score value of the destroyed UFOs.

Sea Monsters
Destroy the monsters at the bottom of the sea, but don't kill the fishes!

Break it down/rebuild
The objective of break it down is to use the least amount of shots to break up the rotating square. The square consists of 24 pieces, 24 being thus the best score possible.

Rebuild is just the opposite of Break it down. Use the least amount of shots to rebuild the rotating square.

Shoot a little / Shoot / Shoot a lot
The objective of these games is to the targets as many times as possible. When a target is hit, it changes color and speed. The difference between the 3 variations is how many shots you can do (20, 50 or 99).