The Extra-Solar Union of Systems Archive

Hi i came across this website while looking for info on a pf hamilton book,ive notaced that this universe created is realy in depth, could anyone let me know what this is , is it a role playing game, or was it created form a tvshow, or books.
If its a game how is it played and how do you join it.

The ESUS is an alliance on the website "Nationstates.net". The ESUSWiki website is used by members to keep track of information about the nation that they roleplay as.