Beautiful game! Well done!
My only wish is that the space flying sections had a little more to do in them. Some sort of obstacle, or thing to look out for.
I will also say, that the forced death levels seem a bit out of place / annoying to solve.
I think you also have some minor collision issues. In the level with the horizontal platform, I got snagged on the floating squares.
There's also some flicking caused by what I assume is your tilemap not being a 100% match to your sprite sheet.
I loved the game!