tactical nukes delivered only to military installations wouldnt be that bad. they werent exploded OVER the bases in the air, they were exploded on ground level. much about nuclear war is exaggerated. the major villain would be the wind currents, carrying radiation. once the war was over, the irradiated sections of the planet were cordoned off (like Chernobyl and Fukushima was...sorta). the entire world looking like the game Fallout is highly improbable, even if every nuclear power in the world fired their nukes. the world isnt as small as people make it out to be.

but that brings me to three other points: in this story, only a couple of countries fired nukes at each other, not the whole world. America was one of those countries but most people living in America dont know who the other country is, since much of the electrical infrastructure is down. Also in my game, the earth's crust is expanding and contracting, resizing and reshaping the planet, as well as causing millions of earthquakes and volcanic eruptions a day. and third, the body count is relatively low thanks to the good angels that most of the population dont even know exist. also, demons use radiation to make possessing people easier. so its all connected. 

Once we get a couple pages IC, the state of the world and story will make more sense, at least i hope.