One cool thing you could implement is the idea of a government debt where a country can get extra money from another country, institution or even plato.
The amount that they are able to lend should be determined like in the real world based on the eCountry credit rating, on the number of citizens, on the past country income, on the new country power (and the empire factor) ...
The country will then get the said amount they want after a vote in the congress about it and they get to pay interest on it (agreed on depending on the credit rating)
This would be a cool new implementation which would evidently favor the big countries at first glance but also be favorable to smaller countries who may need a small push to give them some sort of edge. This will create some sort of economical warfare (if a country borrows from another).
You could also make a bankruptcy option where plato takes over the country economics if the country fails to pays its debts. Plato then increases the taxes until the debt is paid.
Its a cool idea, small countries will gain an advantage when lending a bigger country who will be more favorable to the smaller country lest they decide to call in on the debt ...
