As the previous comment said, the theme implementation is really good and thoughful and is the best aspect of the game. I won't write more about it as the previous comment hits it perfectly.
The mining doesn't really have any gameplay meaning except clearing the way, but with the theme it works. You could have made the resolution a bit larger as I zoomed in the browser to see the game better.
I don't know how much you have worked on games outside of this game jam, but for this being your first one, you did good. You could try some longer lasting jams where you could implement better your creative vision, but learning by doing is the best.
All in all, your game hits different. Good job!