I've occasionally thought it would be fun to have a computer game where you start out with some land, some people and some natural resources, and your job is to found a country and run it. You get to write your constitution, set up laws and so on and see how things unfold. You might also play the part of a politician once the country is set up. You might get voted out, which changes the set of powers you have (and makes the main next objective "get back into power"). Maybe there are other countries on the "virtual planet" - you can invade them, embargo them, make treaties with them etc. They have their own objectives. You get problems thrown at you (war, dissent, natural disaster and so on) and have to make changes to your policies to try to keep everybody happy.
Given the similarities between writing laws and writing code, I suspect this might devolve into a "programming game" style activity (albeit with a rather more political type of geekiness). I also suspect that there are so many aspects of human activity that would need to be simulated that making it realistic would be an overwhelmingly large task. But of course it doesn't need to be perfectly realistic to be fun - it may be fun enough with just easy-to-implement large-scale economic features.