It's a nice concept, it's fun to play.
The balancing was too easy in my opinion. Cards with the “draw x card(s)” effect are overpowered. They're quite common, and as the cards immediately return to the deck after being discarded (without going through a discard pile), it's easy to break the game by drawing infinitely.
I got to the point where I could play almost infinitely without needing to build a new hand.
Having said that, I'm well aware that it's very difficult to have time to balance a game during a gamejam.
I've spotted a bug. At the end of a level when choosing an upgrade, if you click outside the frame, it loads the next level without allowing you to choose an upgrade.
Below, a screenshot of the moment I stopped playing, my character having become unstoppable, condemned to crawl the dungeon forever... spooky stuff :o
