This is a remake of the classic Apple II game called Sabotage which was later redone on the PC as Paratrooper and on the Atari 2600 as Commando Raid. You are the turret gunner and the enemy is the invading paratroopers.
The objective is to shoot the paratroopers, airplanes, and bombs but not the helicopters and the health packs they deliver. Last as long as you can while gaining as many points as possible. In the game, click instructions button for controls and scoring.