The art is eye-catching, and the music is pretty nice (especially given that you'd be hearing it on repeat). Very nice selection of sound effects, too.
Then comes the meat: the gameplay adds a neat twist to the "dig as deep as you can and buy stuff to help you dig deeper" loop. This sort of game's normally not my cup of tea, and it certainly took me a few runs to get used to steering with the mouse (especially when I got the Bite and Saw upgrades and tried to incorporate them into each run), but it became a very fun experience once I did get used to it. And the Bat upgrade really helped me push just a bit further, especially when paired with the Bite upgrade.
I might actually play more of this genre because of this, so good work!