Interesting subject. What about simulations in which simulations are run? Clearly the mathematics of fractals could be profitably brought to bear on the subject. "Simulation," to my mind, is a somewhat fuzzy concept which seems to assume that there is a qualitative difference between a substrate reality and a simulated reality contained therein. From the vantage of someone observing a simulation running within a simulation, no clear criteria seem to distinguish one from the other, beyond the mere given that one contains the other.