In Hearts of Iron the closest thing to a main campaign has always been the German 1936 scenarios, so check that out if you have the time. You lead essentially the Nazi state, which sounds like a total bummer, but you can always roleplay that someone assassinated Hitler and concentration camps were put an end to. But the real point is that you can relive the ball-numbing offensive operations of what was the best army in the world, from France to Russia. If you love looking at maps of famous battles or those cool strategic ones on Wikipedia then you'll be plenty motivated to get into it, it's probably Paradox's least difficult game to master besides Crusader Kings. I didn't have an appreciation for how big the Eastern Front was until:
The Germans have trapped 163 Soviet divisions, around 2,500,000 men. That's only about half their entire army, and slightly less than my entire combined force in France, Russia, and the Balkans. This is how my Barbarossa came out, I thought I basically won but it took me four more years until victory was realistically in sight. For context, it took me half a year to force French surrender and they only ever fielded 100 divisions in total with the UK.
Also, can't you drive any faster Klaus?
edit: started reading the wall-o-texts on this thread. I now understand why the Paradox forums don't let you talk about Nazi Germany at all
added shameless self plug

Also, can't you drive any faster Klaus?
edit: started reading the wall-o-texts on this thread. I now understand why the Paradox forums don't let you talk about Nazi Germany at all
added shameless self plug