Earthsiege 2 continues humanity's struggle against the evil Cybrid race. When the cybernetic A.I. known as Prometheus decided that humanity was not fit to control it's own cybrid race of A.I. machines, it rebelled and made it's purpose to eradicate all human survivors. Prometheus succeeded in destroying most of the human military installations but one. A base hidden from the Cybrid, humans found a stockpile of obsolete HERCS to use in the war. From there, the Earth Resistance launched an assault to take Earth back from the Cybrids and finally strike at Prometheus itself at its lunar base.