Ultra satisfying game; from the simple but beautiful graphics, to the color palette, the upgrades, the balance, everything is astonishingly amazing.
The only thing, if I have to say any, is that the theme of the jam could've been "implemented" further by adding some kind of cost or tax to entering the mining area, or adding some kind of "fuel" instead of a time limit, which would've added a bit more strategy.
Nevertheless, I loved it! Good job!