This is exactly the sort of game I would've played for hours as a kid on friv. Something with incremental upgrades, procedural generation, ah this brings me back.
There were a couple things I ran into during this (other than rocks) that I think need to be addressed. One, I see there are stats for things like visibility and drill strength, but I couldn't find a way to upgrade those in the shop. If it does exist, I think it needs to be made more obvious, because I was very interested in upgrading those.
Another thing is keeping your dig progress after respawning. If I'm not wrong, couldn't you just dig straight down, respawn, rinse repeat forever? It wouldn't be very fun probably but since score is determined by depth reached, I feel like that's the sort of thing that could be used to optimize the fun out of the game.
I was curious so I just tried doing this myself, I keep running into a bug where I get stuck after entering the shop. So I guess, in a weird way, there is something preventing you from doing that.
Potential cheese aside, I had a good time digging around in this!