I really like the narrative reasoning of civ unlocks
While watching preview, I couldn't help but notice that the unlocks came with their own text seemingly explaining the reasons as to why you can now switch to this new civ, and from what I've seen it seems to be a very nice touch!
Here, the Songhai are depicted as a part of your empire, a group that, given the opportunity, could rise to the occasion and take power...which is what would happen if you choose them!
Meanwhile, the Inca are shown as a community living in the heights, sheltered from the crisis that comes with the end of the Age. This makes them a possible contender simply because of the safety they propose to the people in that time of crisis.
I think those are a very awesome way to explain why you could switch to these civs, and it makes me very excited to find all of them! What do you guys think?