The planet Allium is facing a desperate situation due to global warming, causing the polar ice caps to melt and resulting in rising sea levels that have dramatically decreased the amount of habitable land. The remaining island chains are now the most valuable resource on the planet, and survival and competition for them must be ensured.
Two distinct civilizations on Allium, the scientifically advanced Forseti and the aggressive Muspell, are currently at an uneasy cease-fire. The Forseti have recently developed the Battle Engine Aquila, a highly advanced combat vehicle that can switch between modes as needed. Players take on the role of Hawk Winter, a Forseti cargo loader operator who has been conscripted due to his piloting skills.
Battle Engine Aquila is a mechanized shooter set in a larger battlefield where the player's role is crucial in a larger war effort. A significant part of the gameplay involves supporting and being supported by allied forces, as players must fight against naval, air, and ground forces in both modes of their battle engine.