Good job on the levels. As a fellow puzzle dev that was good use of the puzzle elements you have in game so in terms of puzzle design it was challenging but good challenging.
I was impressed you were able to have a sandbox mode in-game. That’s a nice touch. Although you might have left some stuff out to get it in-game I assume.
In terms of music/sound it does become repetitive for awhile but it was not too distracting as I was more focusing on the puzzle itself.
In terms of graphics the static art is great but definitely missing that juice, I think you mentioned it on your page that you did not have time for it.
And for the boss part I have to admit I ran out of brain energy so I had to stop. I got too absorb in getting those 3 stars. so all in all good job! :)