Good find! Definitely looks like they integrated the previous developer into their main team.
Yeah I was impressed by how polished it seemed. Looks like it is by a different developer than the "Dig" games - https://store.steampowered.com/search/?developer=Thunderful%20Development
Still impressive that they've never made a City Builder before though!
The end of Demo said it'll be released this year (2023).
Yeah I really think they did a good job with having a lot of systems, yet still being pretty straightforward to understand. There were only a couple things that I didn't immediately understand (even without reading tutorial text).
Definitely can't wait to see if the full game holds to that pattern!
It is quite a bit different, but as far as games that scratch the "mining" itch, I found this to be really fun -
https://store.steampowered.com/app/361280/Turmoil/