To get to your city it is possible only through a narrow canyon. Arrange with its competently various guns that not one plane or a military vehicle could not take place your defence and get to a city, to defenceless civilians. Each attack occurs time one and a half minute but if you have coped with enemies can include approach of the enemy earlier earlier. For each killed opponent, to you money for which you can buy additional guns are charged. And if collect a money and at all can will buy already more effective weapon.