Personally , I'd like to see a mod which puts sports in the game. It could start with a wonder, olympic stadium, and the first builder gets to host the first olympics not only getting culture and increased income, but also getting more benefits everytime the olympics are hosted in that city. There would be a vote in the UN on which civ gets to host the olympics (or World cup so that the UN's role would make sense historically). Perhaps to get a better chance of winning you could put some spending into creating athletes, or using citizens and making them to athletes. Not sure if it can be done in the code, but it would be nice to see. A win in the world cup would increase happiness,income,and culture for a while.