The base have spotted an illegal trading business on the airport. The base have sent you alone to the location to eliminate them. you have to eliminate all of the dirty armies and stay alive to complete this mission. but beware, the dirty armies are so dangerous and are great in numbers.
Control: Use the mouse to aim and left click to shoot. Press 1 or 2 or 3 to select a weapon, and press spacebar to reload.
A context menu should be shown when right-clicking or, on touch devices, long-pressing in the game. This menu especially allows to play in full screen and control the volume.