Heroic submarine

Do you want to become the captain of a military submarine? Your task is to destroy all enemy ships, sailing past your ambush. With each level the enemy is becoming more and more difficult to sink ships. But there is good news: for the money that you are awarded for sinking ships, you can significantly improve the combat characteristics of their submarine. Going into the army shop, you can reduce the cooldown torpedo installation, increase the speed of rotation of the periscope, to increase the speed and power of a torpedo explosion. The more high-level ship, the more money is charged for its sinking. But keep in mind, for every released torpedo will have to pay, too. Moreover, the more powerful the shot, the more expensive it is. So my advice to you - in the lower levels do not increase the power of your weapons.
In the game there are three levels: easy, normal and hard. Go from simple to complex.
The game will be completed after you are on the first level fail to sink the enemy ship 3. For each passed the level of the total allowable number nepotoplennyh ships will increase by one. Try to pass as many levels of the game.