I liked the idea, first I thought I changed the size by pressing the e button on those white lights on the wall :D Then in like that enemy level I started to realise that it was Q and E that did that :D (Reason for this was that at least on the WebGL build I was playing the hint/controls text disappeared almost immediately, so I couldn't really see what it said :D)
The enemy levels didn't really bring any kind of other difficulty, so rather have different levels or like traps that would make you lose and you would have to start again (that way have to think more on like running towards a wall on the other side to get them perfectly balanced to do it correctly), because once you went all tiny it was just running underneath :D
Creating more puzzle mechanics into this for sure would make it more difficult and I think more playable that way for the puzzle enjoyers, I'm not one of them, so for me this was alright, but I do see that when it comes to puzzles it was very easy. :)