What an interesting concept! It was so wacky to get my head around the idea of a tower defence game with playing cards haha, very creative game and the use of the theme with the subject matter and game genre was great. I felt the progression could have been faster perhaps? Either more money per enemy or less money to upgrade along with waves that increased in difficulty more quickly. I lost health on the first two or three waves and then the enemy chips barely got out of their spawn point for the next 15 waves while I slowly upgraded one card every turn or two. That sort of balancing would be expected with a full game though, for a game jam it's a great effort and well done for such an 'out there' idea! There was a minor bug in that the music cut out whenever the heart shot at an enemy, but otherwise it all worked as expected!
Nice work :)