Leviathan is an Unreal 3 engine game that combines intricate flight controls with fast-paced shooting to create an action game focused on an alien invasion. The player controls the Drone, servant of the giant Leviathan mothership, tasked with defending its master long enough to allow it to devour all that surrounds it. The gameplay consists of flying around the city, defeating enemy ships and turrets that target the Leviathan, as well as destroying any obstacle that stands in the Leviathan's way. The player must monitor the Leviathan's health and occasionally deliver energy cores to restore it as it gets damaged. If the Leviathan manages to reach the end of the stage alive and well, it devours a major part of the city in a fantastic destructive display.