Hazmat troopers

hazmat troopers are aliens from an unknown company which sends them into Old new York's subway and the old underground city, the ones that are sent into the subway are in orange hazmat suits, the berserkers are in red and brown suits with spiked baseball bats. the ones that are sent into the ruins are in green suits with baseball helmets, the Rocketeers are in yellow suits with high powered rocket rifles. all of the normal hazmat troopers are equipped with plasma double barreled shotguns. sometimes once you shoot them they will pick up their gun and fire one last shot and die.

trivia
The same shotgun is seen in The Series Has Landed when the farmer chases bender out of the farm after sleeping with the crushinator.