Harbour Attack by Rajcsányi László is an action game made with GB Studio.
The goal of the game is to move your submarine through the dangerous water to reach the enemy port, then destroy their cargo ship. Among the many obstacles you must avoid are mines, submarine nets, and aeroplanes. To play the game smoothly, follow these three stages:
Stage One: To complete the first stage of your mission, you must guide your vessel through the submarine nets.Your submarine cannot travel at too great a depth or it will be crushed by the pressure of the water.
Stage Two: The next stage is survival. Enemy ships and aeroplanes try to bomb you out of the water. When you have destroyed the ship 10 times, you automatically move to the third and final stage.
Stage Three: To complete your mission, you must destroy the cargo ship which is sailing into port. Position your vessel, then fire between the barges to destroy the ship.