I liked the idea as well! A nice mix of "Plumber" "Snake" and dungeon crawler. I join Oliver about the card orientation, but as there isn't a time limit (?) it isn't a big issue, just some readability kink.
I saw a little bug, however: The sword icon (One that appears after you use a card with a chest in it) remained on the screen after I used it (I used a card with a monster on, while having picked up one sword). I first thought the sword had multiple uses, where it wasn't (used another monster card, without picking any other crates, lost a heart instead).
Cheers!