What happens if your nation runs out of money? I don't think this was ever explained in the tutorial.
Additionally, what happens if you don't have enough food to feed your citizens and soldiers?
It seems odd that treaties are only available between alliances and not between nations. It seems like treaties between individual nations would also make a lot more sense, because it can be hard to keep track of who you need to defend in other alliances versus having a small network of nations to defend.
It would be nice to be able to see a nation's chief import and export, ie what resource the nation has bought and sold the most tons of on the market. Also maybe a chief trade partner which shows what nation they have bought and sold the most tons of resources from. This could even be split into chief import partner and chief export partner.