I really like the game core mechanics. The changes to the world behavior are interesting and creates good environmental puzzles.
Graphics is simple, but functional. I am not sure if the greybox environment is intentional or not, but I actually don't mind them.
I would welcome some character sounds for walking and jumping to add some life. Maybe also some bg music.
Also ocntrols felt a little bit sensitive to my taste. It was making me a little nauseous (especially in combination with toxic fumes effect).
Overall - I had a fun playing your game. Great job!