Here's a series I wanted to try - as Soviet Union fight the whole world at once.
For this I modded in an event where every country declares war on me as soon as I finish the Great Purge. I wanted these to be separate wars, so I used mods to remove factions from the game. And to make it even harder, I played with no annexation rule, just puppetting. And a few other mods.
Unfortunately with so many wars ongoing and a butch of puppet countries, the series started suffering from horrible performance, and I had to stop early.
Anyway, you might still find it enjoyable - there's a lot of action until it gets too slow.
Here's episode 1. The rest will be published once a day.
If you want to try such a thing yourself, you should probably remove the no puppetting rule, and that might just be enough to make performance tolerable.