Hidden Agenda is a great game because it teaches players about the (regrettably limited) decision-space of Latin American leaders during the Cold War, not by lecturing them about their Anglo pretensions, but by letting them take on the role themselves. In fact, Foreign Service Officers from the US were sometimes asked to play the game before rotating to Latin America, to better understand the people they were working with. I don't think enough ostensibly "educational" games make use of this approach.
You'd think that the best exemplar for simulation games that educate would be miltary war-games, right? Fight as Napoleon did, et cetera. Well, next week I'm going to explain why war games teach you very little about actual generalship, with a guest appearance by Guy Debord (yes, the situationist Guy Debord)"I maintain, quite forcefully, that you can learn more about the Roman military, its changes over the course of the Late Republic and the Empire, and the nature of internal conflict in the Empire, by studying Nofi’s game [Imperium Romanum II] than from any six books on the subject. In some cases, games are better than narrative, because they allow you to explore a system, to experiment with alternatives, while linear narrative must stick to the literal events and not the possibilities." --Greg Costikyan