By the word "realistic" I mean, like, if we capture a neutral or enemy city, we should be able to create (or produce) units in it. Like in the REAL World War II, Germany took all the air factories before taking the enemy country so that the enemy had less areas to produce planes and units, and, Germany took over the country easily. I think that when we capture the city (which is not in our country), we should produce units in it and then take the whole country. I basically mean, we should be able to produce units in enemy areas, that's all. Thanks for consideration.
~Varnit.