thanks for sharing feedback :)
while the balance may be a bit weird I can recommend you to try to get the evolved forms of the tools (at least this is how i got very far anyway). But i will lower the difficulty a bit still.
I could put the next level button in the middle but in case you missed you can still continue mining after you reach the goal (which i recommend) so it might obscure some tiles you want to hit. I was also planning on adding effects like tiles showing the money they give upon breaking but couldn't figure it out but i might tackle it some time.
Also if you get the health and damage up for the pickaxe you can get its evolved form "detector" from the shop which allows pickaxe to show the tile under the current one by right clicking.