Loved the graphics and the game as a whole. I would change the player movement a bit so that you always face forward, towards the enemies (though the controls were very smooth and movement was fun) and maybe add a bit of a wind up to the attack, especially the pink laser shooting dudes and the swordfish guys, they just sort of attack out of nowhere.
I also think the implementation of the card mechanic was a bit weird, the buffs just weren't that noticeable to me. I think it may have been a bit better if the player has to pick a card when they get a buff, just to give a bit more player interaction.
I loved the enemies and player characters, they were really well designed, and were clear in their function, bat that shoots you first enemy, bigger bat, swordfish etc. Also loved the background, very subtle but lovely.
Overall very fun game