U-Boat

U-Boat is an arcade shooter where you repeatedly traverse the screen, navigating through an area full of naval mines, while ships are passing by above you, on the surface. You can adjust the depth of your sub and launch torpedoes vertically. For each ship you hit, you are awarded points. Your fuel is limited though and is steadily expended. Additional fuel is lost if you accidentally touch or shoot a mine. Contrarily, if you reach a certain score, more fuel will be added to your reserves, prolonging the session. When you eventually run out of fuel, the game will give you a ranking, according to your performance. The game uses only three buttons, up, down and fire, while there is no directional control whatsoever.