I love this riddle. I first encountered it in `a href=http://infocom.elsewhere.org/gallery/zork0/zork0.html~Zork Zero`/a~, back when that was the only game on the brick-like laptop that I was terribly excited to have all to myself in my room.
Oh my gosh. I just realized, my comic takes place in the sort of world where `a href=http://laughingsquid.com/game-geek-alphabet-by-jared-von-hindman/~grues`/a~ can exist! `a href=http://en.wikipedia.org/wiki/Grue_%28monster%29~Grues`/a~ totally exist in aMoP!