Those of us who have been playing computer games for more than 25 years know that the "Grue" is from one of the original text based game series,
"Zork" (and sequels). In Zork, you had the option of going up, down, right, or left, and in many instances, you received the response "are you sure you want to to do that? You might get eaten by a Grue". And being eaten meant you had to start over from a "save point" - if you remembered to save! LOL!
I remember spending MANY hours pouring over printouts of my "adventures", trying to find where I went wrong. Text based games were great! :D :D
(I still have many of those games, if anyone wants to try them...)