Help defend your sub against the Puffer Fish. The goal of the game is to shoot as many of the Puffer Fish as you can to unlock the next level and get a high score. Shooting 10 shots in a row without missing releases a bonus starfish that you can shoot for bonus points. You have to shoot a puffer fish 4 times to kill it. Shooting a puffer fish that is puffed out will release whatever item(s) it has in it.
Use the up and down buttons to position the sub and the shoot button to kill the puffer fish. The first objective is to kill enough puffer fish to unlock the next level and the second is to get the highest score. Bullets that do not hit anything take points away from your score so use them wisely.