Use the arrows to move left and right. Use up to fire a fishie bullet, which will hurt divers. If you run out of fishie bullets, press r to reload. Use space to fire a fishie bomb, which will explode on contact. These take a while to load, though. Don't let the divers reach the bottom or you die! Post your score and offer recommendations, please.
This is a very short and not accurate demo of the real project being worked on by me and @ultimatepie.