The game froze for me as soon as the timer ran out, so I don't know what happens when it ends. The gameplay loop was solid and there was enough challenge to keep me entertained the entire time. My score was 17.
The pixel art is good, but a little bit inconsistent (mixels :O). I also thought it was strange for some objects to have a solid black outline while others didn't.
The choice of having to right click and middle click seems odd to me, I think the controls would be more concise if you could just right click to chain a piece.
Overall, the game was pretty good. Good job!