This is a pretty cool concept, and I understand the lack of certain features is due mainly to very early development. I'd like to see more base features exist the further the game progresses in development:
- Automation: We lack this a lot. You'd want players to feel like they've finally grown from the constant clicking (not entirely, I will explain later) (or holding click for prolonged amounts of time).
- AutoDrill: I think the way automation should work is that it could be based on a percentage of your DMG stat. The upgrade to use this will increase that percentage by a maximum of 70% so that people can still choose to optimize their playstyle through continuous clicking.
- Dig Speed & Dig Amount: There could be upgrades related to the speed and amount of blocks they're digging, starting with 1 block every 5 seconds to possibly a max speed of 5 blocks per second on any random tile.
- (Sourced from another suggestion comment) Area DMG: I will explain how this will work when we get to the shovel upgrades.
- Explosives: A somewhat better form of automation that deals with Area DMG on a random tile. It's prolonged compared to AutoDrill, but its impact deals with +150% of Area DMG that uses 100% of your DMG stat. Upgrades like Speed and Amount can be implemented at a lower benefit than what AutoDrill would have.
- Shovel Upgrades: As of now, we only have DMG as an upgrade, though I think we could add a bit more to the mix:
- (Sourced from another suggestion comment) Area DMG: The way this works is that you start with a 3x3, with the center now only dealing 80% and the surrounding tiles with only 60%. Each upgrade will add 10% to both center and surrounding damage until it reaches 100% and 80%. If you upgrade it again, it will be nerfed down to 60% and 40%, but you now have a 5x5 grid with the outer area dealing 20%, and you can upgrade that to 80%, 60%, and 40%, respectively as to not make it overpowered to use. Automation can also use this, but it will be nerfed since automation itself only uses a portion of your DMG stat.
- Crit / Crit%: It's self-explanatory, but it could be good if you were to rebalance towards damage and block tile HP.
These are some of the ideas I have. I don't expect you to follow all of it in its entirety because I respect your ideas more than putting any of ours as a 1:1 similar feature, but I will follow through the course of this game's development. Hopefully, it goes well ^^