EU4, although difficult to learn, generously rewards perseverance. The game keeps you in suspense and makes you think about every step, and interest in it does not disappear even after many hours of play. Yes, the game has its shortcomings, but the development team corrects its problems from patch to patch, adding something new to the game every time and does not turn the game into a “cash cow”.
As for the “third Rome” patch, this is just a gift for fans from Eastern Europe! You wanted to try on the role of the Novgorod elected prince and see what would happen if the veche republic were the center of power in the Slavic lands - please. They wanted to repeat the history of Muscovy, the collector of Russian lands - voila! Or they always thought that wise rule of the small Tver, Polotsk or Chernigov principalities could lead these lands to prosperity and make them a new center of power - here you can try that too.
All of the above, coupled with the new religious mechanics and form of government “Russian principality”, “veche republic” and “kingdom” will allow you to plunge into the most interesting, controversial and fateful period in the life of not only Europe, but the whole world!
P.S. Among the obvious shortcomings are the lack of official localization (which can be easily corrected with a fan mod) and the difficulty of mastering.