Loved this one!
Everything is great. Only missing music, but the game loop is very fun and addictive so it's not a big deal.
My suggestions:
- A little more feedback when digging. Maybe something like minecraft "breaking" animation. Specially when you have no upgrades.
- Since the digging is all made in a grid, the character movement would feel better if it was locked on the grid too.

- Just add a "Game Over" message when the player reaches the bottom

Overall, very good job, I've enjoyed this game a lot!

I got all the upgrades and thought to just dig down to see if there's a limit. There is! You just fall through and never be seen again. I consider it a victory and the true ending.

It feels so satisfying when you finally got all the upgrades. Love it. Great job, dev!

Cute little game! Nice retro art, and solid gameplay. Loved the progression idea. I would like more "spice", it's a little bit repetitive after a few mins. But well done!

Awesome game! Love the sound design and the art gives off a very clean, retro look. Only thing I'd add is a way to tell when a block is being mined or not :P

Really cool game. It felt so satisfying to run around on the max upgrade dashing through everything. I even tried to get to bottom of the level by going straight down, which I did manage.  I would argue the game should just run at the last upgrade and the upgrades should be like area clear items, Bomberman style. Great game! Keep it up!