Amazing. If you plan to publish the full game one day, I am playing on day one!
My feedback: Mech armor/visual customization will be added hopefully :) Seeing enemies is hard sometimes. Maybe it is just me, but in some environments, they blend a bit. UI style is amazing, but if the environment is yellow(ish) and the UI border is also yellow, they blend a bit and hurt my eyes. You could make the opacity darker for UI elements during gameplay maybe? Pixel art mechs are awesome, but I think the game would benefit from very small cutscenes (just still images would do because I know how hard it is to animate).
Pros: great sound design, pixel art/3D pixel art, punchy and satisfying effects, cool gun models, and top-notch environmental destruction. All my feedback is personal, so I hope the game will be enjoyable for everyone who knows about mecha/shoot 'em ups more than I do :)
Good luck