Great job on keeping it simple and executing a tried and true concept well. I'm in love with the minimal art style that feels very modern but also a throwback to retro games (and a big fan of the Pico-8 palette). Love the particles and windmills that give it a touch of fluidity you wouldn't get from hand-drawn sprites, but it still blends in well.
I like the sound effects, as well as the music. I appreciate you added a mute music button for accessibility. My only suggestions for controls/accessibility is to add a SHIFT key that slows down your movement a bit for precise inputs, and the ability to hold down X to repeat fire.
Very polished stuff, great job!