A nicely themed game, although I still don't know how we ended up in the rotten wooden room at the start!
Spoilers in following comments.
A couple of issues with the tutorial messages: first, there's no 'mole' object visible in the tunnel, even before you get rid of the mole. The only reason I knew there was a mole there was because of the tutorial message. I know you can't turn the tutorial off in this game, but there should be a 'mole' object there to make it consistent.
Secondly, the tutorial messages don't update after you've completed the puzzles in those rooms - it still tells you to examine the mud and talk to the mole even after you've done those things (and in the mole's case, even after the mole has gone away).
Another thing: I'm confused about what was achieved by unlocking/opening the sturdy door in the coal room. When I first entered the room, I could already go north, south, east and west, long before I found the key or unlocked the door. Unlocking/opening the door doesn't seem to do anything to the game state. Is one of the directions supposed to be blocked when the door is locked?
I really loved the ending with the unicorn!