Haha what a funny game and funny idea. The art is somehow strange but fits the game very well. Also the sound effects are perfect. Pretty cool that you were able to put a lot of features into the game e.g., shop, bounty etc.
Maybe the music could be improved, by choosing something which fits a bit better the funny theme. Additionally I would also make it a bit more clear why you win a duel. Sometimes I had only perfect scores, but still lost. I was not sure why exactly. Was it just bad luck or did I do something wrong? Maybe some kind of indicator which shows you how much power, precision or so you currently have before you go into the fight. Then based on that you could see if you just lost because of bad luck of because your score from the X/Z thingy was bad.
Another detail to keep in mind: There are some strange countries (greetings from Switzerland :D) out there with QWERTZ instead of QWERTY keyboards. So X/Z is a bit an unfortunate combination. Maybe also allow Y as a a key or avoid Z for such things.
Congratulations to this very hilarious game! Well done.