An awesome amount of depth mined (lol) from a simple concept. Really loved this one.
I think the main thing I'd improve is a bit of a clearer explaination for how things worked, but obvioiusly it's a game jam and tutorials are never a priority, so it's only a minor quibble.
I did not successfully mine 3 bitcoins, but I'll be back again after the jam to try again :)