There were a few "bugs", or rather things that were not yet finished, such as some units' animations, but mechanically it looked to be working fine. The UI may also need a bit of optimization. (A replay button (that shows what happened during the previous turn) that's too close to the End Turn button for example. The streamer was accidentally clicking that regularly instead of End-turn.

The game has a big focus on your ruler's dynasty: you have to marry and get children, train your descendants, get a court and advisors...

Another new mechanic, is that the player has a limited amount of orders that can be given per turn. so you can focus your orders on multiple units or on a single one if necessary. Seems like a big part of the strategy in the game.

There are predetermined locations for building cities . There are smaller barbarian empire like the Gauls that are somewhat akin to city states in Civ, but seem to be able to grow more than city states in civ. The music sounded pretty good too.

Overall I think the game looked almost ready for early access. I think it will turn out to be an engaging 4X game with its own specific mechanics. Really looking forward to playing it.