From the About page

What is Xsyon?

Xsyon is a massively multiplayer online role playing game (MMORPG), an online community, a virtual world and an adventure.

Set in the near future, Xsyon is an apocalyptic fable. The world draws its inspiration from history, mythology, and prophecies of the Apocalypse. Most aspects of modern life are now gone. The leaders of the new world, under the guidance of the reinvigorated once forgotten gods, have hidden traces of the scientific progress that led to the devastation of the earth. Modern vehicles, weapons, appliances, computer and even the books that describe these things are practically nowhere to be found.
That one word "Fable" free's up the game to be set in any time.