I love the art style and the music! Really love that retro sound.
Gameplay wise it could be improved, as other comments said, the upgrade pricing seems to jump too fast, and some idle progression would be nice and interesting to implement with the theme of the game.
Also I found a "bug", if you don't purchase your upgrades in order you may get stuck with a low upgrade for a while until you can get a better one (I bought the golden shovel first and then the silver one, and I had to dig with the silver one until I was able to upgrade again.) Maybe making the upgrades additive instead of enabling the last tool you purchased or something would fix that.
Also, I need to know the name of the dude, he seems really cool. He looks like a close relative of Barry Steakfries (From Jetpack Joyride)
Edit: wtf the coment was sent 3 times, I deleted the other 2