I liked this. It was really well made, and should be getting more attention than it appears to be getting. I'm not entirely sure how the theme fits into it, though.
If I had to critique something about this game, it's that the enemy AI is a little too easy to abuse. If I stood near a tunnel opening, the enemies often couldn't get to me, but I could still attack them. This was particularly broken for the final boss.
I loved the idea of character customization using the cards. Applying an affect to both the suit and value made for an intuitive way of understanding it. (For the record, I beat it using the 4 of Spades)