One definition of "universe" is everything that exists. Another definition says a "universe" is everything that exists and is connected (so there can be severa

One definition of "universe" is everything that exists. Another definition says a "universe" is everything that exists and is connected (so there can be several universes that don't interact with each other.) If I create a fantasy world in my head, the people and places exist in my head; if I create a fantasy world in my computer, the people and places exist on my computer. Thus, at least in some sense, they exist. In a way, everything within the simulation makes up a universe; in another way, it's more like a sub-universe that has internal interactions as well as external interactions with the simulation hardware. From the perspective of a simulated character who doesn't know about the computer or my brain, they live in their own universe. (P.S. are you the Suncho from the Descent world? If so, it's good to see you again.)