A recreated synethic world resembling Earth after the mysterious catastrophe, it was made by Borland as a means to achieve resources and hopefully get UnMen to find him in Ariadne’s Maze. Because the world doesn’t exist outside of Borland’s memory of it, it is largely finite. Borland even recreated himself there, but only with enough direction to point UnMen in the right direction.
Time generally does not move forward in a true sense as Borland does not recall the end days so Simulacrum World is essence a running program that repeats itself. Finally, because of the exertion it took to make this and Elephant Temple, Borland cannot make any real changes to it. Beings that leave Simulacrum World cannot go back.