Classic concept with nice puzzles, nice difficulty curve, but i have some suggestions:
1. Use a different background color and make the graphics overall less "unity-like". Nothing wrong with it, but i think that would look better and more polished.
2. Add music.
3. Maybe you could get more people to play your game by using actual footage from your game with a bit of font and stuff as a thumbnail.
I hope the feedback helped you, would be nice if you could check out my submission too. :)