Katzenjunges
The word grue was first used in modern times as a fictional predator from Jack Vance's Dying Earth universe. Vance probably took the name from an archaic/dialectal English verb meaning shudder, now most commonly encountered in the word "gruesome".
A similar monster, whose name was borrowed from Vance's grues, has become a staple of the hacker mythos and computer games. They were incorporated into the Zork series of interactive fiction games by Infocom, and into several of the roguelike games, including Ancient Domains of Mystery (ADOM).
The first mention of grues in the Zork games is the following ominous line:
- It is pitch black. You are likely to be eaten by a grue.
Further investigation (by asking the game) will reveal more about their nature:
- > what is a grue?
- 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.
This warning is not to be taken lightly. If the player attempts to continue moving through a dark place rather than returning to a lit area or activating a light source, there is a high probability he will be caught and eaten by a grue. Originally grues were not a threat as long as one remained still and didn't leave one's location, but in later games it has been possible, in certain situations, to be eaten by a grue simply by waiting around in the dark.
Grues were invented to limit players' options when faced with unlit areas. Without them, a player might attempt to blunder about in the darkness, perhaps (for example) to reach a lighted area beyond a dark passage. The presence of grues ensures that such tactics will fail, and forces players to solve any light-related puzzles first. For comparison, Zork's predecessor, Adventure, used pits to achieve the same result. An adventurer who attempted to move about in darkness in that game had a high chance of falling down a pit and dying.
This made sense in Adventure's environment, which took place entirely inside a natural cave with all of a cave's many nooks and crannies. However, when the original Zork mainframe game adopted this practice by killing players with "bottomless pits", it was quickly pointed out that these pits appeared to exist in unlikely places such as the attic of a house, with no evidence of holes in the ceiling in the room directly below.
Dave Lebling quickly invented the concept of a wandering, light-fearing monster that would be a plausible replacement for the immobile bottomless pits, and, taking the name from Vance's work as having the right connotations, introduced grues in the next version of Zork. The version update document made a humorous reference to the "dungeon maintainers" painstakingly filling up the bottomless pits and restocking the dungeon with grues. Years later, the Zork prequel game, Zork Zero, would feature the protagonist doing exactly that -- forced to use a magic device to seal up the realm's bottomless pits that are blocking his path, he unwittingly forces out the myriad colonies of grues that have been nesting there, leaving them to wander the underground caverns searching for food.
Zork lore
Grues have been featured in each of the Zork games and many other of Infocom's games, becoming a company trademark or in-joke, often referred to with the stock phrases of "slavering fangs", "razor-sharp claws" and "horrible gurgling noises". The science fiction title Planetfall reuses both the "You are likely to be eaten by a grue" line and the grue's description, replacing the word "adventurer" with the current job title of the protagonist. Additionally, Planetfall makes reference to grues having been unwittingly taken from their home planet (which is implied to be the world on which Zork takes place) and introduced to Earth by the alien ship in Starcross, then subsequently spread around the galaxy alongside man and become a universal pest for human civilizations. The term crops up as an in-joke in other contexts as well, such as a racehorse named "Lurking Grue" in the modern-day murder mystery Suspect.
Much is made of the idea that grues have such an aversion to light that no one has ever seen one and it is impossible to gain a firsthand physical description of one and that, conversely, grues are such formidable predators that light is the only possible means of avoiding them. Neither of these ideas held absolutely true throughout the entire Infocom line of games. For instance, the game Sorcerer, which provided a wide variety of humorous responses to creative uses of magic spells, allowed the player to cast the FROTZ (light) spell on a grue, causing a "horrible, multi-fanged creature" from just outside the range of vision to run through the room "gurgling in agony and tearing at its fur". The game similarly provided a potion that granted the ability to see in darkness as a trap for players who forgot that the main purpose of a light source in the Zork games is not to preserve one's own vision, but to repel grues; taking the night vision potion and turning off the light source results in the almost immediate sight of, and subsequent devouring by, a grue.
As time went on the games became increasingly bold in their treatment of grues -- Wishbringer allows the player to stumble upon a baby grue and get a good look at it before its mother returns (described as a "horrid little beast with red eyes and slavering fangs"). Spellbreaker, which had the player traveling through magical planes that represented various elements and principles, had the plane of darkness almost entirely populated by grues and forced the player to survive by using magic to take the form of one of the beasts.
One of the repeated references in Zork's backstory was to the ancient king Entharion the Wise and the legendary blade Grueslayer, which he used to directly fight grues in combat; this feat would not be repeated until the interactive fiction/RPG hybrid Beyond Zork, which allows a player who has advanced sufficiently in level and acquired certain items to boldly walk into the dark and kill grues that attack. It also introduced as its primary villain the Ur-Grue, an evil god of darkness who ruled over the world's grues. Finally, the modern-day game Zork: The Undiscovered Underground created as a promotion for Zork Grand Inquisitor featured an extended reference to a line in Zork III about "a whole convention of grues" in a certain location, by having the player infiltrate a literal grue convention, complete with lectures, entertainment and souvenirs.
That game was the first to give a detailed description of how grues looked, having the player disguise himself as a grue after seeing one and noting that it had a "fish-mouthed head, razor-sharp claws and glowing fur all over". (The reference to light-hating grues themselves glowing appears to be a mistaken interpretation of Sorcerer describing a grue glowing after a light spell has been cast on it -- although Spellbreaker does mention that grues' eyes give off a very small amount of light that lets them navigate in darkness.) However, an actual illustration of a grue had been seen previously, although in an obscure source -- one of Steve Meretzky's Zork gamebooks purposely included a section where the protagonists see a grue face-to-face before being eaten by it, presumably as a way to make the book attractive to Zork fans. Presumably these are not the only instances in the Zork games when grues have been seen -- one event in Sorcerer has the player finding a Frobozz Magic Company "anti-grue kit" (admittedly a secret, experimental prototype) that contains a grue costume, with which the player can don and travel among grues unharmed. (The player in Zork: The Undiscovered Underground replicates this feat, albeit imperfectly.)
This is part of the running gag of a series of (mostly failed) attempts to find some sort of alternate means of protection against grues in the event one's light source fails, most famously in Zork II where a can of Frobozz Magic Grue Repellent was included as a red herring -- useless, since it would only last for one game turn after one's light source expired, during which the player couldn't see his location anyway.
The actual reason light acts as such a potent Achilles' heel for grues is inconsistently given -- some games imply that grues find levels of light ordinary for humans to be intolerably, blindingly painful but can nonetheless survive it (such as in Planetfall, where an obviously grue-like creature exists in a lit laboratory, "squinting and cursing at the light"). Zork: the Undiscovered Underground goes to the other extreme, having a grue caught in the light spontaneously combust on the spot. The question of how grues are able to survive undetected at all without being trapped in a dead end by a wandering human with a lantern has often been debated by fans, attributed either to their ability to squeeze through tunnels humans can't see or to use something akin to Dungeons and Dragons' "shadow jump" ability.
The modern graphical adventure games in the Zork series produced by Activision continue references to grues, with gurgling and growling grue sound effects audible in most shadowy or gloomy places and many points at which players can meet a gruesome death by wandering without light. The in-jokes continue as well, with Zork Nemesis continuing a running gag about failed attempts to capture or domesticate grues by including in a library a book, "Interview with a Grue", that sported an illustration captioned "The Grue In Its Natural Habitat" (a blank black square). Zork Grand Inquisitor added to grue trivia 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."
Other references
Grues are a very common reference in hacker culture among computer-savvy people old enough to have been playing games in the Infocom era. They have cropped up in other fantasy realms, though rarely, as they are seen as being strongly attached to the Zork universe, Infocom and the medium of interactive fiction in general. For this reason many modern interactive fiction works make extensive in-jokes referencing grues; most memorable was a parody work called Enlightenment, which takes place in a Zork-like universe where the protagonist has overloaded himself with an abundance of light sources -- suddenly finding himself in need of help from grues to defeat a troll, he is forced to find a way to extinguish them all.
Grues show up repeatedly in the roguelike game Ancient Domains of Mystery; originally only existing as an in-joke, "You are likely to be eaten by a grue" being one of the stock phrases one can encounter while traveling through the dark, eventually the classic Zork "lurking grue" was added to the game. Present in the dungeons but very rare, someone who is suffering under a serious bad-luck curse ("doomed") has a chance of being "eaten by a grue" at any time while moving through the dark, which is an instant, unavoidable death. Grues were also introduced as actual, very high-level monsters one could fight; among the menagerie of "elemental" monsters such as fire lizards or stone giants were "elemental grues" which were supposedly grues advanced enough in elemental (magic) power that they could "wreath themselves in shadows" and fight against players in the light. Grues are also present in the roguelike NetHack, in which they are one of several monsters that the player may think he or she sees while hallucinating, and in the browser-based RPG Kingdom of Loathing, as a nocturnal fighting familiar that appears as a pair of glowing eyes in a patch of darkness (the Grue can only be acquired in a parodical text-based portion of the game that begins with the sentence "things get a little less... illustrated").
The Adventure/Sci-Fi game The Journeyman Project has a short reference to the Grue. In fact, it is even one of the ways you can die in the game. On the Mars station, if you hop onto the train tracks for the underground rail system and decide to wander off into the dark tunnel, the game ends with a short blurb about being dead, and eaten by a Grue. The Turbo version appears to have changed this, however, to being hit by a car. The death scene then reads "At least you weren't eaten by a Grue!"
In the game The Legend of Kyrandia, if you enter a room in the cave labyrinth without a light source, glowing eyes will appear, slowly moving closer, killing Brandon.
Unrelated concepts also named "grue" include Grue, a municipality in Norway, and grue, an imaginary name for a color derived from the words "green" and "blue".
The on-line comic strip User Friendly makes references to Nethack and games from the text console era (references to "grue"). One of the album collections is titled Even Grues Get Full.
The webcomic Megatokyo references the grue in strip 201.