This is a remake of the classic game paratrooper.
The player controls a gun turret at the bottom of the screen. The turret can swivel to cover a large area of the screen, but cannot move from its base. Helicopters fly across the screen at varying heights, dropping paratroopers. The gun may fire multiple shots at once, and the shots may destroy helicopters or shoot paratroopers. Paratroopers may be disintegrated by a direct hit, or their parachutes may be shot, in which case they will plummet to earth (splattering and dying, killing any paratrooper they fall onto). Periodically, jets may fly by and drop bombs; the jets and bombs may be shot as well.
The player earns points by shooting helicopters, paratroopers, jets, and bombs. Firing a shell costs the player one point, so if one is playing for score, there is an incentive to conserve ammo.