The theme is cool, your straight interpretation of it works well and your ending is very funny.
I enjoyed the game and I like many things about it. I really like the music in the first stage, the difficulty feels right overall, how the transition from a level to the next works and you can still walk for a few seconds after Victory message appears, the different enemy behaviours and the different bonuses are cool.
In in the first stage in particular I wished the game felt a bit more dynamic and frantic, in this one you'll probably just never get two enemies on the screen at the same time and you'll just dig when there's no enemy on the screen so it feels a bit off at this point. Near the end it got quite better though' as the time melted while bats kept harassing me.
With a character looking so much like Arale, and holding a shovel of anything, I probably could not have resisted making something involving poop, so kudos for resisting the temptation ;).
Well done, thanks for sharing.