The Single Gatling is a immobile enemy which fires bullets at you in a fast rate.Appears since the beggining.
The Double Gatling is an upgraded version of the Single Gatling that can fire faster. It looks similar, but has two cannons instead of one cannon.
Appears since the beggining, too. (?)
Skies of WarEdit
The Gatling is also an upgraded gun in Skies of War where it can deal more damage than conventional machine guns and is also an enemy gun in later levels. The original turrets in Rail of War also reappear, as either friendly or hostile entities.