How much gets left out of simulations is highly dependent on the cost of simulations and the interests of the viewers.

We might be in a naturalistic simulation where what we'd call boring people are as carefully simulated as anything else. I'm much more willing to bet that other galaxies are merely sketched in.

It seems reasonable that if we're in a simulation, then the universe we're simulated in has much more resources than we do. There would still be more and less elaborate simulations, but the odds of being in the range where how interesting you are matters strike me as too small to bother with. It's like trying to optimize winning the lottery when you're an average person, but with much less scope sensitivity. (Mathematicians occasionally find a flaw in a lottery.)

I've been playing with the idea of what do you do if you get out of the Big Box, and I don't think it's take over the world-- it's get your universe copied on to more different computers, possibly on to more different platforms. I'm not sure that people like us can run directly on their physics.