I have my hands on the 'demo' version of this. I will be starting with a First-Era Nubia game. Atleast that's what I'd always do in CK1, as it's the most challenging empire to carve from nothing. North African Orthodox Empire of Europe, go!
Is it even possible to survive as Nubia? Shia Caliphate + 2 holy wars always end that state pretty quickly. The only way I was able to survive was to swear fealty to the Caliph, which is only possible as Axum as kings can't swear fealty.
It's very possible, I remember I expanded from 1-territory Kingdom of Nubia, managed to actually win the first war that Egypt declared on me (due to major internal strife, civil war, and revolt) which allowed me to take 3 high-yield provinces from their southern border. I eventually worked my way from Egypt, all the way through the holy lands into Mesopotamia/western Asia [note: each war was massive, the Muslim people know how to resist] and then curbstomped the Byzantines and made Thrace my new capital. After about two generations the empire eplit into two chunks, one situated in Mesopotamia and the other in Egypt. I decided to play as my Babylonian successor as he had ridiculous stats (15+!) and processed my brother into my empire. Then the world was falling apart, as Rus didn't even get close to being united by any of the Rurik clan, and the Christians were having all-out chaos in mainland Europe, basically leaving the Orthodox empire to rule as it wished.
Skip forward about 120 years and I had most of the southern half of Russia, along with the Baltics, the northern coast of Africa, Hispaniola, and last but not least the crown jewel of it all: Roma. I had a grand total of about 13 kingdom titles, with COUNTLESS Duchies sprinkled along the way. Many of the titles I got to create myself as the AI was nowhere near as efficient as I was, hah. Probably the most fun I've had in a Paradox game. I remember I played that specific dynasty for almost a year real-life, playing different branches and usurping the Emperor with different pretenders.
I also turned all of my lands into, yep, you guessed it, Orthodox Christianity. No stone was left unturned to destroy the powerbase of Catholics and Muslims.
It was a rather epic time. One I'm going to recreate with the (heretic Orthodox) Abbysid lands. I just started and thanks to Axum, I already have the small Muslim nation to my east inside my borders. Next to Axum, and then I will get to unite Ethiopia and conquer from there.
First impression: The UI is bad. Really bad. I don't like how they made it about a million times more unwieldy to do simple things. Also, what the hell is this shit with not allowing women to be Chancellors or Stewards anymore? If ONLY males can be the four useful councilors, then what's the point of finding a well-skilled woman as your bride? Genetics? Eh. I hope modders fix that very, very soon.