This is one of my first games. There are still some errors in it.
You have to shoot the ships at the top. The other ships are shooting back.
Ships with red crosses cannot be destroyed. If you crash them, you will die. You shouldn't touch any ship at all, because you will lose a live if you do that.
The green bar shows your oxygen. If it gets low you have to go up to the water level and refill your oxygen.
The gray submarine, which is coming, when you don't have any ammo, gives you ammo and oxygen.play the game