Sometime in the 22nd century, humans have fullyĀ terraformedĀ and colonized Venus and Mars. The Neosapiens, an artificially engineered race created to beĀ slavesĀ for the Terrans, haveĀ turned against their mastersĀ and formed theĀ Neosapien Order/Empire/Commonwealth. Under the rule of the calculatingĀ Governor General Phaeton, the Neosapiens have launched an invasion of Earth and Venus. The ExoFleet, the Homeworlds' space navy (in particular, Able Squad, a group ofĀ Exo-FrameĀ pilots led by Lieutenant J.T. Marsh), fight against the invasion in an interplanetary war to protect the Terrans.