Really nice visuals, the sprite casting shadows is not something you see often. The ship having momentum was also novel, don't know if for the better but it certainly gave a different feel. As for the screen movement the others mentioned, while the current situation isn't ideal, I think it could go in different ways, letting the camera move just horizontally while the backgrounds scroll down. Or leaving it as it is, changing the backgrounds to fit an arena like place, and maybe even letting the player rotate the ship.
Good effort overall!