I know that Fallout has almost nothing to do with realism, but according to American WW3 scenarios from the sixties, a nuclear war between the Soviet Union would probably look like this:
1) A full-scale nuclear war (started by the soviet limited strike) variant
a) The USSR launches its bombs in a limited strike - only the most important military and industrial targets are hit. Europe is almost left intact.
b) The USA launches a counterstrike on military and industrial targets in the USSR.
c) The soviets send a message that they want to stop the hostilities. If the Americans won't agree, they will launch a full scale attack against civil targets in USA.
d) At this point the most destroyed countries would be USA and then USSR. The Soviets proposed a cease-fire because after the war is over, they would start a race to take over Europe.
e) The next phase would depend on the decision of the american president - but we are Fallout fans and want a "full nuclear war scenario". So America gets nuked badly, and so does Soviet Union.
f) And what about Europe? If the Soviets wold belive that they could tak e over Europe after the war, they would hit only military tagets. If not, well - the Eiffel Tower (and the rest of Paris, and London, and Berlin, and other cities) goes bye-bye.
2) A full-scale nuclear war (started with a limited strike launched by the America to prevent the Soviet strike)
a) Basicaly as above, but USA gets hit less then the USSR, the chances of a full scale war (initiated by the Soviets) is bigger, and thus Europe can get a bigger piece of the action.
3) A conventional war escalation to nuclear war variant
a) Turmoil in one of the border (or near border) countries, probably Italy, Hungary, DDR nad Poland, or less possibly in the Balkans starts a conventional war. The Soviet Union launches a full scale armored attack on Western Germany. And starts wining.
b) In this situation, according to the NATO doctrine (obviously opposed by the Germans) eastern parts of DDR and western parts of Poland get nuked with tactical warheads to destroy russian suply lines.
c) The soviets suspected this and were experimenting with the use of air bridges to supply whole armored divisions (and by "coincidence" all divisions stationing in DDR had a full ABC protection). And now they have a good occasion to use tactical nukes agains NATO. Basicaly, at this point, Germany and a part of France is probably reduced to glowing rubble.
d) Then, one of the sides would probably warn the other side, that if they use more tactical nukes, it will launch a strategic nuclear strike.
e) It could end with a nuclear cease-fire... that probably would be broken if one of the sides would start loosing.
f) Of course the result is a limited nuclear war with a high probability of turning into a full-scale war.
g) And Europe is basicaly nuclear rubble.
Unfortunately, this scenario does not fit in the Fallout universe, as the USA isolated itself from the rest of the World.
This means, that the most probable scenario of war in Europe would look like this:
4) Conventional soviet strike in Europe; nuclear war triggered by the nuclear exchange between USA and China.
a) The Soviets, although marely a shadow of their initial power, want to take over Europe, which is devided and suffered badly during the resource wars.
b) The European countries quickly understand, that theye are in big truble. Probably after the fall of Germany the UK and France would try to make an alliance; their only hope is to cripple russian suply lines in Eastern Germany with a tactical nuclear strike. The soviets haven't got enough resources to launch an air bridge.
c) Soviets launch thier tacticals and state, that further use of French and British nukes will result in a soviet strategic strike against targets in those countries.
d) The offensive continues, although it goes badly as the soviet supply lines are almost nonexistant. The war turns into a stalemate.
e) During this stalemate, both sides prepare for a nuclear exchange...
f) which occurs when one of the sides, China or USA, launches their bombs. Probably American bombs were not aimed at Russia and Europe, because it would make no sense; instead, Russia got hit by China because of a conventional conflict between those countries.
g) Soviets understand that they are already f*cked, so they probably launch a attack against Europe - they hope, that their forces dispatched somewhere in Europe can take advantage of the fact that Western Europe gets bombed by them, and that soviet goverment and at least a bit of their economy can survive the war.
h) Eventually, Europe is FUBAR, Russia is FUBAR. The worst hit teritories are Eastern Germany and a bit of Western Poland, second are Western Germany and Eastern France, most of Britain and the European parts of Russia get bombed by strategic warheads and are rubble. Italy, Spain and Portugal are probably less destroyed.
