There's a bunch of sci-fi that depicts simulations of reality. From crude virtual reality in things like Lawnmower Man, to the more recent Matrix or Inception (maybe even Tron?). The underlying mechanics for how the simulation works tends to vary, but the idea of an unreal world that's similar to the real one is a long-running sci-fi/fantasy trope.
I don't think we have a tag for this. What would be a good tag for works involving fake realities?