For what you are looking for, you need an agent-based model of the economy, i.e. the economy modelled from the ground up. Top-down models will not be able to capture unknown unknowns.
The closest to what you are looking for that I know of is this: https://github.com/crisis-economics/CRISIS.
I'm not sure if this is exactly what you're looking for but I felt like I learned more from the indie game Capitalism Lab than I would have from an MBA.
I'm not sure what would you like to simulate, but in the economy, you build models with a set of features you assume should influence the outcome, and then you can measure how well your model explains the reality.
I'm not sure if you're right that such a simulator would be valuable. The thing is that we already can explain quite well what's happening and have the means to fix stuff, but frequently there's no political will to do so.