Wow, this is so cute! You really nailed it with regards to the theme for this jam, it's very clever, great job! You should continue developing this, there's a lot of potential. :) I'd love to see some music for the overworld, and some ways to mix up the gameplay, like powerups (perhaps an invisibility cloak?) Perhaps also making it generate a new map later on after getting out of the tutorial stage.
I'd also recommend tweaking the challenge curve, something I found a little frustrating is that I ended up doubling back multiple times to try and find a secret passage I must have missed, but didn't realize until I accidentally grazed a baddie that they don't deal damage to me, and when attempting to interact to talk with them, only then did I find out you can hide treasure with them. The conveyance could use a slight tweak there. Somewhat related, the trap door tile in the first room was confusing at first so I got caught on my first try while attempting to figure out how to hide treasure in it, haha. Whoops!
Oh! and not sure if it's a bug (and if so, not sure if you're aware) but somehow I managed to get negative keys and couldn't get rid of my remaining coins. Hmm...