I loved the idea of puzzle pieces to fit the Joined Together theme. The levels were well designed with some interesting mechanics to work with, who doesn't love portals. My only issue was having the change character and reset buttons bound to buttons that are adjacent on the keyboard, I kept accidentally clipping the R button when going to press F to change characters and resetting the level.
Other than the one minor issue I really enjoyed the game and hope you revisit it in the future and add some more levels and new mechanics to it.