I was thinking post nuclear world, not falloutish. More twilightish.

The goal being to manage whatever fragile peace of civilization you have and rebuild the world. The soldiers of NATO and Warsaw would have gone home, formed their own communities, or would have become bandits and raiders along with the civilian populations.
Warfare would have taken terrain more into consideration. You have a terrain map in addition to the political map. There would have been radioactive marshes, each province having a chance to contain urban ruins, mountains, hills, plains, forests, deserts, tundra, etc.
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Basically the world is not totally barren like Fallout is

Think of stuff like that and Metro2033, and STALKER.
Some Nations like the US and USSR would have remained, however the US's Western states would have either fallen to anarchy or formed their own self ruling governments. USSR would have been dealing with attacks from rebels, raiders, and some religious theocracy from the east. Communist China was able to annex Taiwan, but lost most of territory. Then new nations pop up, each following their own ideals such as democracy, fascism, socialism, theocracies, dictatorship, republics, confederacies, etc.
A majority of the provinces are unclaimed, but your military has to claim them. Each one is full of hostile natives and wildlife. Expand too fast and you are likely to fall into anarchy, expand to slow or not at all you risk getting overrun or stomped out by your competition.
You basically trying to make a strong, stable, and secure nation. Rediscovering technology can help, or going Roma and marching all over the world. Or being like Switzerland and creating and unattractive, but defensible position.
In addition to that production and technology would play a factor. To build certain things you need the technology for it. Technology/knowledge could possibly be found in the ruins, researched, or traded for. In addition to that you would need to scavenge and build up a industry to feed your army. So trade would come in handy here to. Being a nation that makes a lot of bullets could make you a lot of best friends.
But there would be too much to be managed and you would basically need it to be made into a video game to do all this.
However I donate these ideas to inspire.