In the distant past, they awoke from beyond the Moon wielding impossible powers, and gave humanity an ultimatum - surrender or perish. Some believed them to be harbingers of the apocalypse, others bowed to their will, but many chose to fight back.
Harnessing the forbidden power of psychics and creating the massive Machina, they brought the war to space. But, even these were beaten back and obliterated. Now, the Selenon have wiped out seemingly all of humanity... except for the few that remain under the Bureau's protection.
The City contains what is seemingly the last of humanity. The Bureau of Human Protection functions as its government, sending its Enforcers to keep the peace... and the agents of SPECTRA, the Special Counter-Technology Reconnaissance and Assault force, to prevent lost technology from being used against the Selenon.
The agents of SPECTRA are special - they are psychics, humans who have received the powers of the Selenon in order to carry out their will. But, such power also comes with a curse. Those who refuse to obey the Selenon or fail in their duties will face the ultimate punishment. For an agent, as with the Selenon, failure is not an option.
An energy dome from ancient times stretches over the core of the City. While it may once have protected it against the Selenon, today, its power has waned, and it can only stop the constant meteors that fall upon the city.
While those lucky enough to live in the Inner City are so consumed by their busy lives that they forget it's there, the denizens of the Outer City see it as a constant reminder of their station, worsening their disdain for the Bureau.
The Inner City has thrived due to its location under the Dome. Many buildings from ancient times still stand here alongside more recent ones. A center of business and entertainment, only the middle and upper class can afford to live here. The heavy Enforcer presence also means that crime is relatively low, though there are still some seedy parts of town.
For many denizens of the Inner City, it can be easy to forget about the world outside. As long as the Bureau does its job, most people here would prefer to live under the gaze of the Selenon if it meant preserving their livelihoods.
The area outside the city is where most of the lower class lives. Few remnants of the past survive, due to the constant meteors that fall here. Those who strive to be a dome-dweller live in the shadow of the City's walls, while the dregs of society live closer to the inhospitable Badlands.
The deadly meteors that fall upon the Outer City are a constant reminder of the presence of the Selenon, who have made it impossible to extend the Dome's protection. This has made it a hotbed of rebel activity.