Looks great! The music fits well, and the shooting is satisfying, especially with those particle effects. I've had some minor issues, however. There is a small thing that I think most Unity users forget about, which is to set the supported aspect ratios in the player settings. This causes the game to render incorrectly on 4:3 or 21:9 displays. Overall I like the pixel art, but I think there are pretty big differences in resolution (the balloons seem to have a lot less pixels than the background).