This game is an amazing step up from the first one! I got addicted just after some time!
You should definitely make sprites of connected buildings for every building!
Speaking of which, there needs to be better differentiation between buildings. Some of them look too similar and could be confusing if we happen to put them near each other.
But I still feel that wood is vastly underused in the late game and easily piles up, just sitting there, especially since some important late-game structures passively use up stone, whereas does not seem to be the case with wood.
There's one mechanic that I found significantly interesting was the ability to control the birth rates. It feels like a feature that is possibly more powerful than any other mechanic or structure in the game. Like, set it too low for too long, and you could end up dealing with underpopulation. If you don't exactly want careful management to be a factor here, I think you should create some kind of warning when there's an estimate that you're gonna lose too much population if the existing trend of low births rates continues.
Also, I think it's a little annoying that we can only make blocks over empty space only if both sides of the blocks are connected to another block. It's a welcome addition that building blocks over empty spaces was at least added, though.
Another tool that could definitely be useful is perhaps graphs that can show us some details on change in happiness, population, and various resources.
Also, perhaps allow us to tear alien ruins down when they're fully explored.
I think you should also add some kind of unlockable sandbox mode where we're not bound by resources to build.
And you NEED to allow us to pan around the map with the arrow keys. Zooming out from side and zooming into the opposite side is killing me!