Incredibly fun game! The gold generation felt very nice and natural, the animation of Sam is great, and I like the challenge of trying to balance getting to lower levels while trying to get enough gold to make upgrades. The 20 seconds left music was a fantastic touch, reminded me of Crypt of the Necrodancer. Overall I'm incredibly impressed this was able to be made in such a short time!
My main criticism is that W/X for A/B felt very awkward for me and I had to stop playing due to a cramping hand. I'm totally going back later to try and get more endings though.
I had a few little bugs in my handful (4 or 5?) of playthroughs - ghosts catching me while I went into holes, the day-end screen appearing with the spacing at the top instead of the bottom of the screen, gold getting stuck in the border walls, and a stall that lasted about 10 seconds (after which a ghost had stolen all my money).
Some clearer documentation of mechanics on the game page would make starting up a little easier, I thought the dynamite was needed to get to lower floors in my first run lol. Worked it out soon after though.
I think if one were to add another upgrade choice to this game, a gold magnet (so that mined gold in a certain radius is pulled towards you) would be a good addition.