I love the way you've made this game look. The post processing effects are awesome and the lighting is just great. It honestly feels like I'm looking through an old CRT TV screen. The parallax background is really great as well. I love the use of physics for the cannon balls, so I can bounce them off the ceiling to kill the enemies below. That said the game is obviously very short, but there is such a lot of potential in here and you've done so many interesting things that this might be the first game where I actually go and check out the github repository and see if I can learn a thing or two. Great job.