It took me a death to mushrooms to figure out that I should not touch them at all, at least not until much later. I enjoyed the game all through to the end. In particular, I liked the way the secret walls were introduced. Very good level design there.
The danger of the mushrooms could perhaps have been done a bit nicer so that the player could recuperate after attacking them too early. Now you sort of had to restart.
Then they added a very good tension in the puzzle-rooms where you had to avoid them. Only thing there was that in the one where you had to get a key too, that they key was a bit too hard to spot.
There were some obvious problems with UI scaling too, which can be seen in the video.
All in all though a very nice game.
Playthrough: