Things I liked:
-Fun puzzle game! I love puzzle games and this one was well thought out and super cool as small mechanics were introduced to think about how they could interreact with each other and create so many unique puzzles!
-smooth transitions from character to character to make switching and exploring not feel punishing but something I enjoyed doing
-glad you had a menu you could view controls in game that were easy to find and understand
Things to improve:
-you already noted the bug about how they can climb on each other. I accidentally left the map because of this bug.
-Would love some artwork on those main characters and some more SFX to make them unique. Maybe including some hints that the red one can go in the fire, blue can go in the steam, and green can drop a bone
-introducing the bone mechanic more clearly. I read the controls before so I was aware, but I am sure someone would have difficulty with it
Overall:
Super fun puzzle game that I would love to see more of and play again! I even showed some friends this because I thought it was so cool! Good work!