Neat little puzzle game, reminds me of when I used to make flash games and post them on Newgrounds.
A save feature and a level select screen would be a possible improvement, just a few more levels and you'd have a lot of people not able to complete it all in one sitting. Another minor thing is to that a more pixelated font would fit more with the pixelated graphics. A BGM may also be considered too, whether using your own or any of the free to use ones from NG.
Also interesting that you used Godot Engine on this, since I've heard about it recently although I'm more familiar with Unity myself.
Good luck with your future creations!