Short and sweet. Definitely somethin' that could be expanded upon much more in the future, with a bit of additions here and there.
I was a bit confused at first at what was goin' on, but I figured out that the money you accrued in each dungeon run was permanent for the shop. It would probably help just a bit to give some context to what you were supposed to do beforehand or something to get the player acclimated a bit more easily. Other than that, there wasn't any kind of bug/issue I could find.
A few things you could add are different paths, random enemy encounters, and possibly a bit of story here and there.
I think one thing that could make this a bit more engaging is at certain points, the player is given the option to continue or return to the start to use the shop. This could add in a pretty interesting incentive later on, where if you choose to continue you'll net more gold, but if you die you'll lose half of your acquired gold that run.
All in all the building blocks for a great little game are all present within and could eventually lead to something great. Pretty good job so far, though.