Having to throw bombs when there's noting left on the screen feels a bit silly - maybe have some kind of upgrade/reward currency for full clears with bombs left over? Right now there's little point in staying strategic once you've got a bunch of the chaining upgrades, so it gets less interesting in the mid-to-late game.
Still not a fan of the music but thank you immensely for letting it be turned off! Huge quality of life upgrade.
The core gameplay loop is good; I did find myself sometimes wanting to stay in the mine rather than always being kicked out to the upgrade screen, though the mining payouts are so generous you can quickly go through the whole tree in <30 minutes.
With some more levels or challenges, I can see this becoming a very good game.