"Fabula Nova Crystallis Final Fantasy XIII (Fabura Nova Kurisutarisu Fainaru Fantajī Sātīn?) is the collective name of a series of games made under the Final Fantasy XIII label by Square Enix. Made in the same vein as the Compilation of Final Fantasy VII and the Ivalice Alliance, Fabula Nova Crystallis (which means "the New Tale of the Crystal" in Latin) is based on various worlds and different characters, but each game will be "ultimately based on and expand upon a common mythos." According to Square Enix, they all take place in separate worlds and there is no cooperation between the teams of the various titles -- the only connection being a "vague crystal theme""
While the mythos is still present in Final Fantasy XV, it was "disconnected" from the core framework, with specific terminology being removed and its emphasis reduced to become a background element for the world and story.