I liked the movement and for only 4.5 hours of work, it's surprising how playable the game is! The player could move out of the view horizontally, but vertically they stay in view. I see what you were going for with the rise and fall theme with the sin(x) movement for the enemies. If you make that amplitude higher, it would be much more apparent. I also really liked the lighting and particle effects as well as the overall arcade-like theme!