constructed world

A constructed world (also conworld or sub-creation) is an imaginary world, usually associated with a fictional universe, built via a world building or conworlding process. A constructed world typically has a number of constructed cultures and constructed languages associated with it. Worlds are often created for a novel, video game, or role-playing game, but sometimes for personal enjoyment or its own sake (see geofiction).
See more at Wikipedia.org...