Lovely mining game!
It was fun to try out all the different interactions, and I see a ton of potential to expand on this in so many ways! For example, interactions between bats & boulders, more ways how bombs could interact with stuff, adding items like ropes/ladders and their interactions with the level... the possibilities seem endless!
I think my biggest suggestion would be to give the player a goal or conflict up front to act as the motive. Like, maybe the player needs to buy something expensive as part of a story, and that can only be achieved by progressing far into the game. Or maybe there's a competing mining company that you're trying to be better than, somehow. Just something to drive the core gameplay loop ^^
...wait who's putting these doors at the bottom of the levels O_O