I started a game with Hesse, just because I was bored.
Hesse has nothing special, really, except the fact they start with 3 provinces and thus can expect to be slightly more powerful than their immediate neighbors, without any strong realm around to be afraid of : Burgundy, Austria and Bohemia are all several provinces away from them.
Vaguely thought about trying to form Germany - which for sure would not have been my very first try, but I tend to quit long before it is done cause it's just too damn long until you get the 10 cored provinces you need, while struggling to solve the problem of spending long decades with illegitimate HRE territory. But I got quite lucky from the beginning this time and decided to keep on.
How lucky ? Well, my starting king died after 8 months without an heir and I got a new one from the Luxemburg dynasty, with excellent diplomatic skills. He soon got the "Claim on our rivals" event... Then I kept on getting fine missions which granted me cores on several of the required provinces to form Germany. Then I became HRE and could use that powerful special CB : Imperial Ban... against the Teutonic kinghts who had gone too greedy on HRE territory.
At that point I was starting to feel quite confident that I would possibly manage to form Germany before 1550. To be honest I must say that there was a certain amount of save & reload when I wanted to keep on getting the appropriate missions... when it's time to annex your vassal and get cores on his key provinces, and you're very focused on this goal, you don't really want to waste your time and money in a naval race against England or building a University in a random province.
Here I was well on my way and suddenly noticed that my 6 stars diplomat was still inservice after 82 years... not bad. I didn't feel very comfortable about my heir's awkward name though.
I was concerned about Burgundy for quite a long time, but I punished them at the right time and released Flanders, that I force-PUed some years after... I didn't have to deal with Austria : for almost 50 years they had an Empress who couldn't compete for the HRE crown, and remained without an heir... so I just had to wait and get lucky again until I PUed them as well. Then I inherited both these powerful realms at once with a bunch of wealthy cored provinces. Oh, and I also vassalized Bohemia, Switzerland and Savoy, so I would not have any serious opponent left in the HRE - and Prussia of course.
And finally, here we are. I kept feeling sorry about that Adolf Kaiser, so I might have chosen a certain date to form Germany...
... 18 years later, the unification of Germanic land was complete - here my prestige is low because I had to dump a lot of vassals in order to immediately annex them with the Reconquest CB, rather than diplo-annexing them one by one every 10 years.
I think I'll stop that game here. Of course, there still would be some work to do about the HRE territory, and actually, anything else would be possible to do from that point - I don't think I've ever been so ridiculously overpowered that early with any other country. Germany is truly blessed. But you know, here in Europe we have mixed feelings about the mere concept of Germanic expansion
... I already wanted to apologize to Poland for stealing so much territory from them.