Paratrooper is a 1982 computer game, written by Greg Kuperberg and published by Orion Software. It was based on a 1981 Apple II game called Sabotage which was developed by Mark Allen.
The player controls a gun turret located at the center of the bottom of the screen. The turret can swivel to fire on a large portion of the screen, but it cannot move from its base. The gun can fire multiple shots at once.
Helicopters frequently fly at varying heights across the top portion of the screen, dropping paratroopers as they go. The 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 if they were sufficiently high when hit). Furthermore, destroyed helicopters turn into shrapnel, which may destroy other helicopters or paratroopers.
Periodically, jets will fly by and drop bombs in an attempt to destroy the player's gun turret; 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.
The game ends when the player's turret is hit by a bomb or when a single paratrooper lands directly on the turret. The game may also end if the paratroopers are able to assault the gun turret. This happens after four paratroopers land safely in the territory on either the left left or right side of the turret (that is four on one side, not four total between both sides). The four paratroopers are then able to build a human pyramid so that one can climb on top of the turret and blow it up.
In 1992, Software Creations released a DOS remake of the game called Night Raid. More recently a Windows remake was released by Foppygames called Manotrooper.
Source: Wikipedia, "Paratrooper (video game)", available under the CC-BY-SA License.