I recently came across a decade-old multi-player computer game called e-sim and I thought it had a really cool concept. 

It's essentially a very intricate simulation of the economic and political dynamics of the world. Every new player is a citizen of some country and participate in all kinds of economic, political and military activities in order to improve their country's global standing. It's almost like a visualization of an alternate political world. This webpage explains the concept in more detail. The game still works online (though it has horrible UX). 

Although the concept was cool, and gained some traction, it never really took off because it wasn't very well implemented and maintained. That said, I loved the concept and would love to see a modern remake of either E-sim or some variation of the concept. The modern version would have better UX, leverage better tech, be more adapted to today's audience, and most importantly be mobile-friendly (the original game was browser-only).

I think this game concept as a lot of potential – it not only would be pretty engrossing and fun (think Clash of Clans), but also end up teaching the users something about the complexities of the economy and global politics. Somebody build this please!