Good level designs for the puzzles. I got stuck on the 2nd level. After growing bigger, I wasn't able to fit though what looked like a wide enough hallway. I restarted the level a couple of times before it worked, and I am not sure if I did anything different that time.

The level desing is very good and the art style is simple but really effective, the only problem is the jump button, it feels a little bit weird (Jumps only after releasing the button) but in general it is a great game, Good Job.

Did  you put jump on "keyUp" event? That is not great, not great at all, especially on levels where you need to run and jump before door closes again. 

Othewise - pretty responsive and fun game