In an unspecified time, presumably the distant future, the vast majority of Earth's population is wiped out by a cataclysmic war known as the "Great Destruction." The two largest corporations, Chrome and Murakumo Millennium, constantly battle each other for supremacy. However, the competition provides endless opportunities for the Ravens, mercenaries who exist independently of the corporations. The player pilots an armored core (AC), which is a giant mecha robot. (wikipedia.org)