Yes this is in process. I see Grue as creatures from a plane of darkness. They are nearly elemental. Non material, manfiesting motion and solidness in a quest for food/ energy. They can cross over, through any true darkness, to any realm. There they occassionally feast on beings stupid enough to travel in "their places" without a torch or light.

The grue is a sinister, lurking presence in the dark places of the earth. Its favorite diet is adventurers, but its insatiable appetite is tempered by its fear of light. No grue has ever been seen by the light of day, and few have survived its fearsome jaws to tell the tale.

Full Description
What few descriptions can be garnered include the stock phrases of "slavering fangs", "razor-sharp claws" and "horrible gurgling noises". A more complete description includes a "fish-mouthed head, razor-sharp claws and glowing fur all over". The fur glows only in response to the light being shined on it.

The purpose of torches in most adventuring situation have more to do with Grue than vision. Many an adventurer has died after taking a potion that grants the ability to see in darkness; taking the night vision potion and turning off one's light source results in the almost immediate sight of, and subsequent devouring by, a grue.

The question of how grues are able to survive undetected at all without being trapped in a dead end by a wandering people has been debated by scholars. They seemt have the ability to "phase" from one pool of darkness to another.

Additional Information

The version update document made a humorous reference to the "dungeon maintainers" painstakingly filling up the bottomless pits and restocking the dungeon with grues.

Someone accidently unleashed these things by filling in the bottomless pit. He unwittingly forces out the myriad colonies of grues that have been nesting there, leaving them to wander the underground caverns searching for food.

NOTE TO SELF: Used by Dungeon Masters and their minions

One of the repeated references in Zork's backstory was to the ancient king Entharion the Wise and the legendary blade Grueslayer

The Primary villain the Ur-Grue, an evil god of darkness who ruled over the world's grues.

grue caught in the light spontaneously combust on the spot.

the idea of the game "Grue, Fire, Water", a variant of Rock, Paper, Scissors wherein "Grue drinks water, water douses fire, and fire scares grue.

Grues are a common reference in hacker culture or among computer-savvy people. They have cropped up in other fantasy realms, though rarely, as they are seen as being strongly attached to the Zork universe.

Dungeons & Dragons RPG
a species of intelligent, evil elementals from the Inner Planes, presented as an alternative to the usual neutral, nonsentient summonable elementals of D&D. Aside from a reference to their being "born in places of darkness" on the Inner Planes and a general sense of shapeless menace, they have very little to do with their Infocom namesakes, despite having been introduced soon after the first Zork games