I have to say it is a pretty novel game idea.

Sadly the progression is meh. You can easily rush everything "active" in 15 minutes by focusing on maxing the pickaxe and available ores. Then all that is left are pretty poorly priced villager (passive gain) upgrades that hardly break even or even come close to the last pickaxe. The furnace upgrades can be practically ignored. Only notable outcome of buying these passive gain upgrades is new ring unlocks... but I hardly cared at that point.