Hello! I think there are a few things you could do to improve your game. Here's a few suggestions:
-Make tiles for all edges so they'll all look rounded. For example the single-tile column top looks out of place because the outline suddenly ends.
-Better button design; the blurry circles and arrows seem a bit crude. How about a single transparent color and a thicker arrow?
-What you show so far seems early in development and relatively simple. More enemies, moving obstacles etc. could help with variation.
-The backgrounds/tiles could use some more work; the pixel/photoshop contrast is very obvious.
It helps if you mention what you want feedback on and tell people about the stage of development you're in what you're aiming to do. Hobby/for fun?
Happy game-making!