It doesn't even matter. There's a much more profound problem with the notion of 'simulation' beyond a very surface level of 'establishment of plausibility' (and I'd say for anything that isn't pretty small scale even plausibility is just 'sounds good'). The reason for this is the sheer thinness of the actual formulation of the world in question. In principle you COULD work out the outcomes of basically almost everything in the real world, unless it hinges in some extreme way on very small factors that simply aren't tractable mathematically (IE did it rain on the 35 day of the war or not).
For example, we can't really simulate any of the ecology of our fantasy world, because A) ecological factors are fundamentally energy transfer functions, and we don't have anything like data on net energy flows in our fantasy ecology B) it doesn't HAVE a well-defined initial state because no GM in existence inventoried the populations of every species in their fantasy world C) we don't even know the actual underlying laws, not even their form, for a D&D-like magical world. I'm sure I could come up with a D, E, and F without a lot of trouble. If we have no idea what the ecology of this world will actually do, then how can we simulate population dynamics, and the corresponding cultural effects, etc. We can surely make up these things, but then they are made up, and not part of a simulation.
Likewise with politics, economy, social dynamics, and on down the line to individual behavior beyond fairly trivial cases. All we can do is invent 'sounds plausible' statements about basically ANYTHING in the world, and from there we can invent 'sounds plausible' events and such which it sounds like might follow from them. You might 'do some calculations' or something somewhere in this sea of plausible sounding things, but all their inputs must also be simply plausible sounding inputs!
The kind of detail required to predict anything literally does not exist in a fantasy world. You are FAR FAR WORSE OFF than the CIA in the real world. They can potentially acquire sufficient information to predict SOMETHING, but the very concept of causality itself is not one that can be entertained in a fantasy world! There are no rules, no actual state of the fantasy world, etc. Heck, I expect that the CIA will get a lot better at its job as soon as 'AI' gets a bit better, as their ability to note correlations and perform inductive reasoning about things will increase vastly. Such techniques are impossible to apply to non-existent worlds which include very few facts.