The visual are nice, I really like the lighting, animation of the cards and the attacks. The boss are really cool, there are so many different bosses and each of them have a second phase which different attacks. The music are nice too, basically everthing makes sense.
The gameplay are cool, the card based attacks are really interesting, tho there is a bug where if you selected a path and spamming space, the level will not start and keep adding more, and you will get something like this:
Maybe your code is something like when the path button is pressed it add one to the level number, and then you didn't disable the button when it playing the pressed animation so it can be pressed again mid animation and run the code again and restart the animation? Also im not sure if it is also related to this or Im just didn't realized it before but the boss can jumped out of the platform after that.
But still, really cool game!