Post World War 4, the remaining nations of Earth have worked together to change how humans collaborate. The four remaining factions after the war have a single government and operate as a federation.
Humanity was on its last legs, after World War 3 in the year 2028, with a nuclear winter compounding the issues of fallout zones and billions of people wiped out. However, no one anticiapted the rise of a new race of humans, known as the Chromos, who had significant chromosone mutations, giving them higher intelligence and strength, but also nasty tumors and defomaties. The Chromos bred and evolved their own society, blaming the remaining humans for their fate. The Chromos developed their own military mallitias and attacked many of the remaining camps. This uprising was dubbed World War 4 - but was really more of an uprising.