The origins of the Civilization Game lie in the dark depths of /b/ circa the Summer and Fall of 2010, where a small community of tripfags began to run a variety of CYOAs with content ranging from such lofty literary heights as incestuous rape and school shootings. One such variant of these CYOAs came to be known as Civilization, in which the denizens of /b/ would collectively decide upon the actions of a fictional society.
The cornerstones of these Civ games were the selection of race and starting location, as well as poorly drawn maps done in MS Paint. Some featured a system of conflict resolution involving post numbers, but most simply allowed the tripfag running the game to decide the outcome of any option selected. Typically the person running the game kept track of things like population, technological advancement, infrastructure, and territory.
Circa the Fall of 2011, these threads started getting autosaged and deleted on /b/. There was no specific incident that led to their banning, but gradually the threads died out entirely. One of the people who ran these sorts of games, King Alfonso, transferred to /tg/ and continued to run the games there. Naturally this led to an outcropping of others running similar games, and over the years they've shifted away from their original incarnation.