The Final Use for a Computer
Well, they could play God.
With a sophisticated computer they could make a planet with "real" people and these people would be no different than us. They would program their physics just like what we see so that no contradictions would exist ... then ... they could break the rules occasionally just to scare the bejeesus out of the folks in the computer (or for any other reason). Something like Matrix.
Though no conceivable computer of any size or constitution could recreate an entire universe, they wouldn't have to create a universe ... just what the people could see and most of the program would run itself (a nature program running with the people program). Thus, in the background there would be a star program as part of the nature program which would populate the sky with stars. When an astronomer in the people program looked through his telescope the star program would call up suitable details for him to see and "set" that particular star so that other astronomers would see the same thing.
If someone goes to an uncharted island, the nature program which was governing the development of that island, supplies greater detail as the visitor explores it ... then "sets" the new data in the nature program so an individual (noticed) plant would develop with suitable detail. Look around you. Did you ever notice the amazing amount of detail in the world? Sure you have ... but ... have you also noticed that it's not infinitely detailed. And if you need glasses like me, your particular people program needs even less detail. And ... if most of the people are really stupid ... you'd hardly need any detail at all. In fact, they might only be the details in some smarter person's individual sim-program.
running inside of
Sim Nature ver. #567774.0
Now if this were us, we could explain ghosts, UFOs and every other conceivable anomaly ... and ... we could go to heaven when we die! (If we are found to be worthy by our God)
Perhaps many future advanced inhabitants of Earth will operate their God Program within the same Sim Nature program. So that multiple Gods could compete with one another for the hearts and minds of the Sim People ... uh ... Sim City ... er ... Simp Town ... hmmmmmm ... Yes!!