Zork I Atari ST cover art
|Release date(s)||1977 (PDP-10)
1980 (Zork I)
1981 (Zork II)
1982 (Zork III)
Zork is one of the earliest interactive fiction computer games, with roots drawn from the original genre game, Colossal Cave Adventure. The first version of Zork was written between 1977 and 1979 using the MDL programming language on a DEC PDP-10 computer. The authors—Tim Anderson, Marc Blank, Bruce Daniels, and Dave Lebling—were members of the MIT Dynamic Modelling Group.
When Zork was published commercially, it was split up into three games: Zork: The Great Underground Empire - Part I (later known as Zork I), Zork II: The Wizard of Frobozz, and Zork III: The Dungeon Master.
Zork distinguished itself in its genre as an especially rich game, in terms of both the quality of the storytelling and the sophistication of its text parser, which was not limited to simple verb-noun commands ("hit troll"), but recognized some prepositions and conjunctions ("hit the troll with the Elvish sword").
- 1 Story
- 2 Commands
- 3 Development
- 4 Releases
- 5 Reception
- 6 Legacy
- 7 See also
- 8 References
- 9 Further reading
- 10 External links
Zork is set in "the ruins of an ancient empire lying far underground". The player is a nameless adventurer "who is venturing into this dangerous land in search of wealth and adventure". The goal is to return from exploring the "Great Underground Empire" (GUE, for short) alive and with all treasures needed to complete each adventure, ultimately inheriting the title of Dungeon Master. The dungeons are stocked with many novel creatures, objects, and locations, among them the ferocious but light-fearing grues, zorkmids (the GUE's currency), and Flood Control Dam #3—all of which are referenced by subsequent Infocom text adventures.
Several treasures and locations in Zork suggest that there used to be a large aristocratic family called the Flatheads, which had twelve kings (an author named Boswell Barwell wrote a book called "The Lives of the Twelve Flatheads") who reigned supreme over the GUE. Some Flatheads are named after historical figures; for example, in Zork II, one treasure is a portrait of "J. Pierpont Flathead".
In each game, there are several light sources the player can pick up and use, among them a battery-powered brass lantern and a pair of candles, which both have a limited lifespan, as well as a torch that never expires. The player must be carrying at least one light source at all times when exploring the dark areas of the games, or else, if he or she continues navigating through the dark, the player will be caught and devoured by a carnivorous grue, ending the adventure in defeat. The exception to this rule occurs when the player must use a spray can of grue repellent to navigate dark areas requiring an empty inventory in order to traverse.
The original MIT version of Zork (also called Dungeon) combines plot elements from all three of the following games, which were made available for commercial sale.
Zork I: The Great Underground Empire
The game takes place in the Zork calendar year 948 GUE (although the passage of time is not notable in gameplay). The player steps into the deliberately vague role of an "adventurer". The game begins near a white house in a small, self-contained area. Although the player is given little instruction, the house provides an obvious point of interest.
When the player enters the house, it yields a number of intriguing objects, including a brass, battery-powered lantern, an empty trophy case, and an Elvish sword of great antiquity. Beneath the rug a trap door leads down into a dark cellar, which is revealed to be one of several entrances to a vast subterranean land known as the Great Underground Empire. The player soon encounters dangerous creatures, including deadly grues who only prey on their victims in the dark, an axe-wielding troll, a giant cyclops who cowers at the mention of Odysseus, and a nimble-fingered thief who makes mapping the maze difficult by removing or scattering any items that the player might drop to leave a trail.
The ultimate goal of Zork I is to collect the Twenty Treasures of Zork and install them in the trophy case. Finding the treasures requires solving a variety of puzzles such as the navigation of two complex mazes and some intricate manipulations at Flood Control Dam #3.
Placing all of the treasures into the trophy case scores the player 350 points and grants the rank of "Master Adventurer." An ancient map with further instructions then magically appears in the trophy case. These instructions provide access to a stone barrow. The entrance to the barrow is the end of Zork I and the beginning of Zork II.
Zork II: The Wizard of Frobozz
The player begins in the Barrow from Zork I armed only with the trusty brass lantern and the elvish sword of great antiquity from before. The purpose of the game is not initially clear.
The Wizard of Frobozz is soon introduced. The wizard was once a respected enchanter, but when his powers began to fade he was exiled by Lord Dimwit Flathead. Now bordering on senility, the wizard is still a force to be reckoned with. The player's goal in the wizard's realm is to avoid his capricious tricks and to learn to control his magic.
Zork II is notable for two notoriously difficult puzzles: the Bank puzzle, in which the player must figure out how to walk through several bank walls in order to figure out how to get out of bank with the loot from the vault without tripping the security alarm; and the Oddly-Angled Room, a diamond-shaped room filed with panes of glass representing baseball bases. The player must figure out how to traverse the diamond in order to open a door that will lead to the game's finale.
Like its predecessor, Zork II is essentially a treasure hunt. Unlike the previous game, the ten treasures are tied together by a crude plot. Finding the treasures does not end the game, nor are all the treasures needed to finish the game. Instead, the adventurer must figure out a way to use the treasures in order to reach the game's finale.
Zork III: The Dungeon Master
The player begins at the bottom of the Endless Stair from Zork II.
Zork III is somewhat less of a straightforward treasure hunt than previous installments. Instead, the player—in the role of the same "adventurer" played in Zork I and Zork II—must demonstrate worthiness to assume the role of the Dungeon Master.
The player must get past the Guardians of Zork, with the complete garb of the Dungeon Master, and then endure a final test. The player must be wearing the amulet (found at the bottom of the lake), the cloak and hood (received when the player chooses to look under the hood of the vanquished opponent in the Land of Shadow rather than deal the final blow), the staff (received from the man at the Cliff for helping him retrieve the chest of valuables; attacking the man in any way or trying to take the valuables from him inevitably breaks the staff), the strange key (found in the Key Room when the player uses the grue repellent (from Zork II) to get past the dark places), the royal ring (retrieved from the Royal Museum by using the gold machine to travel back to the year 776 GUE), and the black book (found in the Royal Puzzle).
Unlike Zork I and Zork II there is a time-sensitive event, an earthquake which is randomly triggered about 130 turns into gameplay. The player must retrieve the key before the earthquake (when the Aqueduct is broken, leaving no escape route from the Key Room) and can't complete the Royal Puzzle or retrieve the ring until after the earthquake (when the unopenable Great Door breaks). Also unlike the previous two Zork games, the lantern is of little relevance. It is needed only to walk through the dark areas of the Junction, Creepy Crawl and Foggy Room at the beginning of the game (often done after completing the Land of Shadow, Cliff, and Flathead Ocean—saying "Hello, Sailor" to the Viking yields an invisibility vial—tasks). Another light source, the torch from the Scenic Vista, is used to retrieve the repellent from Zork II and deposit it in the Damp Passage via the teleportation table to provide a light source for the return journey after retrieving the key.
Once the player has all the items, they must give the waybread to the elderly man in the Engravings Room, who reveals himself as the Dungeon Master once fed, to find the doorway leading to the final hallway. Here the "elvish sword of great antiquity" is used to block the beam in the Beam Room. Next the adventurer must get through the Guardians of Zork. This can either be accomplished by using the complicated Mirror Box or by simply drinking the invisibility potion in the vial from the Flathead Ocean. When the player knocks on the Dungeon Master's door he will only open it if the player is fully equipped (see above). He then tells the adventurer that he will obey their commands and follow them to help solve the final puzzle. The corridors lead to a parapet which overlooks the fiery cells. Reading the book here reveals a map of "The Dungeon and Treasury of Zork" which has 8 cells, one of which with a bronze door that leads to the Treasury of Zork. The eight positions of the dial in the parapet correspond to the 8 cells. The adventurer must use trial and error at this point to summon the cell with the bronze door and have the dungeon master return it to its original position by replacing it with any other cell. The key will now unlock the door revealing the Treasury of Zork, which contains the wealth of the Great Underground Empire as well as a controlling share in FrobozzCo International. After this victorious discovery, the Dungeon Master appears and transforms the player into a duplicate of himself, signifying the player's succession to his position.
Steve Meretzky said in 1984 that "the worst bug that ever got out was in Zork III"; having the sword during the last puzzle makes the game unwinnable. "We call things like that our 'fatal errors'; we caught that one relatively early on", he said.
In the Zork games, the player is not limited to verb-noun commands, such as "take lamp", "open mailbox", and so forth. Instead, the parser supports more sophisticated sentences such as "put the lamp and sword in the case", "look under the rug", and "drop all except lantern". The game understands many common verbs, including "take", "drop", "examine", "attack", "climb", "open", "close", "count", and many more. The games also support commands to the game directly (rather than taking actions within the fictional setting of the game) such as "save" and "restore", "script" and "unscript" (which begin and end a text transcript of the game text), "restart", and "quit".
The first adventure game, Colossal Cave Adventure, had been written by Will Crowther in FORTRAN on the DEC PDP-10 at BBN in 1975. Colossal Cave was a basic treasure hunt that took place in an analog of Mammoth Cave. The game used a simple two-word parser that became a common staple of later games in the genre. The game was quickly copied around the PDP community, where it was found on the Stanford University machine by Don Woods in 1976. Woods contacted Crowther and received his blessing to make an improved version. This was soon found on many machines, including the PDP-10 at MIT.
Zork and Dungeon
Dave Lebling recalled that after Colossal Cave reached MIT's Laboratory for Computer Science, "For a couple of weeks, dozens of people were playing the game and feeding each other clues ... Everyone was asking you in the hallway if you had gotten past the snake yet." In the spring of 1977, wanting to play more such games—and believing that they could improve on Colossal Cave—Lebling, Marc Blank, and Tim Anderson decided to write one in MDL (referred to as "muddle") on their PDP-10 running the ITS operating system. Muddle was a LISP-based system that provided powerful string manipulation, so while the two games were similar in that they used text commands for input and were essentially based on exploration, Zork was much more advanced technically, allowing longer and more specific commands. Zork also used a completely new map that was designed in multiple areas with their own stories and self-contained puzzles, whereas Cave was purely exploratory. While Colossal Cave has been referred to as a simulation of Mammoth Cave, Zork has been referred to as a simulation of Colossal Cave, but much sophisticated; The Boston Globe in 1984 stated that "Zork bore about the same relationship to Adventure as the splashiest arcade games do to the little white light that bounced through the primitive Pong".
By the summer of 1977 the game was runnable, although only about one-half its final 1 MB size. The team, now referring to themselves as the "imps" (presumably, short for "implementers"), continued to add new sections to the map throughout the summer. The game initially ran only on ITS, but a port of muddle to TENEX was available, which they further adapted to run on TOPS-20 after they were granted an account on a machine running it. This version was made widely available as users copied it about the early ARPANET, and a mailing list dedicated to the game soon appeared. Over the fall the final sections of the game were added, along with the D&D-inspired combat system, and the game was essentially complete. The imps continued working on the game over the next year, adding further areas and puzzles, with major development completed by the fall of 1978. The last addition was not made until February 1979, but development continued on bug fixes and touchups, with the last mainframe release in January 1981.
The word "Zork" is a nonsense word, often used by MIT hacker as the name for any unfinished program until they were ready to be installed on the system. With the game complete, in 1978 the team renamed the game Dungeon. By this time the game was already quite popular and becoming relatively well known in gaming circles. Some time in 1978 the developers received notice from Tactical Studies Rules (TSR), the publishers of Dungeons and Dragons, who claimed the game violated their copyrights. To avoid any legal wrangling, they changed the name back to Zork.
While being developed at DM, the game's source code was protected by encrypting the files and patching the machine's copy of ITS to not allow access to the directory containing the source code. One enterprising MIT hacker was able to re-patch the OS to allow access to the directory. He copied the source directory to a TOPS-20 machine and began trying every possible password until the files were readable. Bob Supnik, a programmer from Digital Equipment Corporation, used the decrypted source to create a Fortran IV port, which allowed the game to run on the smaller PDP-11. Bob released his version in January 1978.
As Fortran compilers were available on practically every computer of the era, new versions were soon available on many platforms. The source for these versions were taken in the era when the original game was still known as Dungeon, and they all retained this name as they were ported about. For this reason, through 1978 the game was known under both names, and versions with the Dungeon name remained for years.
The Fortran version of Dungeon was widely available on DEC VAXes, being one of the most popular items distributed by DECUS. It went through multiple modifications both to incorporate more features from the original and to track changes in the MDL version. In the late 1980s, the Fortran version was extensively rewritten for VAX Fortran and became fully compatible with the last MDL release. It had one extra joke: an apparent entrance to the Mill (a reference to DEC's headquarters) that was, in fact, impassable.
It also had a gdt command (game debugging technique, a reference to the DDT debugger) which enabled the player to move any object (including the player) to any room. Use of gdt required answering a random question requiring deep knowledge of the game. The game's response to a wrong answer ("A booming voice says ‘Wrong, cretin!’ and you notice that you have turned into a pile of dust") appears in many "fortune cookie" databases.
The Fortran version was also included in the distribution media for some Data General operating systems. It was used as an acceptance test to verify that the OS had been correctly installed. Being able to compile, link, and run the program demonstrated that all of the run-time libraries, compiler, and link editor were installed in the correct locations.
In 1979 three of the four original imps founded Infocom as a general programming firm. Two other members of the DM team, Joel Berez and Marc Blank, had both moved to Pittsburgh and kept in touch, considering the future of Zork. When they heard of the formation of Infocom, they contacted them and convinced them it was possible to sell Zork commercially on the emerging home computer platforms. However, these systems generally did not have a Fortran compiler, and definitely not MDL, and used floppy disk systems storing around 180 kB, or even using cassette tapes for storage.
To solve the language problem, Berez and Blank came up with the idea of having their own computer programming language known as "Zork Implementation Language", or "ZIL", which would run within a virtual machine known as the Z-machine. The Z-machine would be ported to various platforms in shells known as the "Z-machine Interpreter Program" or ZIP. Using rented time on a TOPS-20 machine, they built the first ZIP during 1979.
To solve the problem of storage space, they first considered using data compression, and later decided to simply remove sections of the game until it would fit on a floppy disk. Dave Lebling drew a circle on the Zork map so it contained about half of the original map, about 100 or so locations including everything above ground and a large section surrounding the Round Room. The rest would be used for future versions. The map was modified in a number of places to clean it up and make it more logical, as well as sealing off locations that formerly led to areas of the map that were now being left out.
Berez and Blank moved back to Boston, and Berez became the president of the company. The new game was running on TOPS-20 ZIP and a new PDP-11 version of the Z-machine by the end of 1979. They then purchased a TRS-80, where Scott Cutler brought up a ZIP early in 1980. The team began looking for ways to market the game and turned to Personal Software (PS), the distributors of VisiCalc and likely the first software distribution firm for micros. They demonstrated Zork in February, an agreement was arranged in June, and sales began in December.
PS had no interest in the PDP-11 version, so Infocom retained the distribution rights. This became the first official sale for Infocom in November 1980, when a copy was shipped out on 8-inch floppy along with a hand-copied version of the manual. Sales of the TRS-80 version though PS followed the next month, selling 1500 copies over the next nine months. Bruce Daniels' Apple II version began sales in February 1981 and PS sold 6000 copies by September.
As soon as Zork began shipping, Lebling began converting the remaining half of the map to ZIL. However, this was eventually broken into two parts, both modified from the original, to be released as Zork II and Zork III. While Zork I is very similar to the first half of the original game, the sequels are very different from the second half; for example, in II the player cannot return to the white house. Zork II was offered to PS in April and licensed in June 1981, but by this time Infocom had grown concerned about PS's commitment to the game. Although Infocom was not privy to this fact, sales of VisiCalc were so strong that PS was starting the process of dropping other titles and becoming VisiCorp. Infocom took over distribution in October and set up their own supply chain, releasing both the renamed Zork I and Zork II in November 1981.
Through 1982 the company completed the port of Zork III while also writing new ZIPs for Commodore 64, the Commodore Plus/4, the Atari 8-bit family, the CP/M systems, and the IBM PC. The entire line was released on these platforms when Zork III shipped in the fall of 1982.
When Zork became a commercial product at Infocom, Infocom agreed that if an Infocom copyright notice was put on the Fortran version, noncommercial distribution would be allowed. This Fortran version, and C translations thereof, have been included in several Linux distributions.
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The original version of Zork I was published by Personal Software in 1980 for the TRS-80 and was simply called Zork, but Infocom later handled the distribution of that game and their subsequent games. The Personal Software version was distributed in clear plastic bags containing only the game disk and a 36-page booklet. Infocom's first "self-published" version of Zork I was in the so-called "Folio" format which included a single piece of paper describing how to run the game. The feelies noted below were only introduced when Zork I was re-released in the "Grey box" format.
Zork I was one of five Infocom games that were re-released in Solid Gold format with in-game hints.
There is also an abridged version, called Mini-Zork I, dated November 24, 1987. It was released free of charge as a promotion.
A German language version was developed, but never released. An unfinished version of this story file, dated January 13, 1988, has made its way into public circulation. The German is evidently non-native, containing many spelling and grammar errors. It is known that Jeff O'Neill worked on this version.
A remastered version of Zork I: The Great Underground Empire (
Zork I was also included in Call of Duty: Black Ops—there is an easter egg where players can escape the chair at the title screen and walk around, where the full game can be played at a terminal computer found in the room.
Infocom did not begin their tradition of including feelies, or extra items related to a game, until the 1982 release Deadline. Later re-releases of the game, however, were packaged with the booklet "Froboz Mumbar's The Great Underground Empire: A History" and a map roughly corresponding to a portion of the game's area.
Although the back of the Zork I "Grey box" depicted a zorkmid coin included with the other feelies, production difficulties led to the coins' omission from the packages. Zorkmid coins were not included as feelies until the release of the Zork Trilogy boxed set.
The Zork series was very successful. Infocom sold more than 250,000 copies of the three games by 1984 and more than 680,000 copies through 1986, or about one third of Infocom's total game sales.
Zork I was the best-selling game of 1982, with 32,000 copies sold by the first half of that year; almost 100,000 copies in 1983; more than 150,000 copies in 1984, comprising more than 20% of Infocom's sales that year; and a total of 378,987 copies by 1986. Based on sales and market-share data, Video magazine listed Zork I fifth on its list of best selling video games in both February and March 1985, and II Computing listed it fourth on the magazine's overall list of top Apple II software as of October–November 1985, and first on the games list. Zork I's sales surprised Infocom by rising, not falling, over time; many dealers sold the game as an essential accessory to those purchasing new computers, including the DEC Rainbow, TI Professional, and others that most people did not see as game machines.
BYTE declared in 1981 that "No single advance in the science of Adventure has been as bold and exciting" as Zork. The magazine praised the sophisticated parser and quality of writing, stating, "That the program is entertaining, eloquent, witty, and precisely written is almost beside the point ... Zork can be felt and touched—experienced, if you will—through the care and attention to detail the authors have rendered." It concluded, "Somebody, please, let me know when [the sequel is] done." Jerry Pournelle wrote in the magazine in 1983 that he played the game with his sons, stating that "If you liked Adventure and wanted more after you solved the Colossal Cave, I guarantee you'll love Zork". 80 Micro called Zork "complicated and sophisticated ... a joy to play". It praised the documentation ("Take it from a rank amateur; these instructions are clear and easy to follow"), and wondered if the game could be solved because "the program lets you do pretty much what you want to do, even if the consequences are much less than desirable, it leaves open marvelous opportunities". The magazine concluded by hoping that "we can expect a second part sometime soon". The Addison-Wesley Book of Atari Software 1984 gave the game an overall A+ rating, calling it "THE definitive adventure game".
In 1992, Computer Gaming World added Zork I to its Hall of Fame, waiving the normal criteria "in favor of honoring this venerable classic." On March 12, 2007, The New York Times reported that it was named to a list of the ten most important video games of all time, the so-called game canon. The Library of Congress took up a video game preservation proposal and began with the games from this list, including Zork.
Zork II sold 173,204 copies by 1986. Softline praised the game's well-balanced mix of humor, wit, and wry puns". The magazine warned of its difficulty, but concluded that "Zork II is recommended to any novice or master adventurer who wants a feeling of satisfaction upon completion of a well-thought-out and imaginative adventure". PC Magazine stated that "Zork II's appeal is universal" and that the game was "a challenge. It is interesting, difficult, frustrating, and most of all, enjoyable. For those who have plenty of time, the game is endlessly amusing". The Addison-Wesley Book of Atari Software 1984 gave the game an overall A+ rating, stating that it "has the same outstanding command flexibility, wry humor, and word recognition of Zork".
Zork III sold 129,232 copies by 1986.  Creative Computing's reviewer wrote that "in my opinion, Zork III is the best of the series". The Addison-Wesley Book of Atari Software 1984 gave the game an overall A+ rating, calling it "perhaps the most entertaining of the three" and with "an unexpected and novel twist" in the ending. The book concluded that "Zork III represents a highwater mark for subtlety and logic, and is a Four Star must". K-Power rated Zork III 8 out of 10, calling it "the most intelligent text game for a microcomputer that we've ever seen".
The Enchanter trilogy:
Games that take place somewhere in the Zork universe:
- Wishbringer: The Magick Stone of Dreams (1985, Infocom)
The Zork Anthology comprises the original Zork Trilogy plus:
- Beyond Zork: The Coconut of Quendor (1987, Infocom)
- Zork Zero: The Revenge of Megaboz (1988, Infocom)
The Zork Quest series:
- Zork Quest: Assault on Egreth Castle (1988, Infocom, interactive computer comic book)
- Zork Quest: The Crystal of Doom (1989, Infocom, interactive computer comic book)
After a five-year hiatus, the following games were produced:
- Return to Zork (1993, Infocom/Activision)
- The Philosopher's Stone (Activision, unfinished text prequel to Zork Nemesis)
- Zork Nemesis: The Forbidden Lands (1996, Activision)
- Zork: The Undiscovered Underground (1997, written by Michael Berlyn and Marc Blank (original Infocom implementors) and released by Activision to promote the release of Zork: Grand Inquisitor)
- Zork: Grand Inquisitor (1997, Activision)
The Enchanter trilogy and Wishbringer occupy somewhat unusual positions within the Zork universe. Enchanter was originally developed as Zork IV; Infocom decided to instead release it separately, however, and it became the basis of a new trilogy. (In each trilogy, there is a sense of assumed continuity; that is, the player's character in Zork III is assumed to have experienced the events of Zork I and Zork II. Similarly, events from Enchanter are referenced in Sorcerer and Spellbreaker; but the Enchanter character is not assumed to be the same one from the Zork trilogy. In fact, in Enchanter the player's character encounters the Adventurer from Zork, who helps the player's character solve a puzzle in the game.) Although Wishbringer was never officially linked to the Zork series, the game is generally agreed to be "Zorkian" due to its use of magic and several terms and names from established Zork games.
Compilations and adaptations
Among the games bundled in The Lost Treasures of Infocom, published in 1991 by Activision under the Infocom brand, were the original Zork trilogy, the Enchanter trilogy, Beyond Zork and Zork Zero. A second bundle published in 1992, The Lost Treasures of Infocom II, contained Wishbringer and ten other non-Zork-related games. Activision's 1996 compilation, Classic Text Adventure Masterpieces of Infocom, includes all the text-based Zork games; the Zork and Enchanter trilogies, Wishbringer, Beyond Zork and Zork Zero. Activision briefly offered free downloads of Zork I as part of the promotion of Zork: Nemesis, and Zork II and Zork III as part of the promotion for Zork Grand Inquisitor, as well as a new adventure: Zork: The Undiscovered Underground.
Four gamebooks, written by S. Eric Meretzky and taking place in the Zork universe, were published in 1983-4 by Tor Books in the US and Canada, and Puffin in the UK: The Forces of Krill (1983), The Malifestro Quest (1983), The Cavern of Doom (1983), Conquest at Quendor (1984). Together, these are known as the Zork books.
Infocom adapted the games into a series of books. Of six novels published as "Infocom Books" by Avon Books between 1988–1991, four were directly based on Zork: Wishbringer by Craig Shaw Gardner (1988), Enchanter by Robin W. Bailey (1989), The Zork Chronicles by George Alec Effinger (1990) and The Lost City of Zork by Robin W. Bailey (1991).
Zork I is featured in Activision's 2010 game Call of Duty: Black Ops as an Easter egg. In the main menu of the game, the player can get up from a chair and find a computer. Typing "zork" into this computer will start Zork I. Zork I is fully playable within Call of Duty: Black Ops.
References in media
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In the TV series Chuck, Zork is mentioned as a game that the title character and his friend, also a CIA agent, used to play when they were younger. Commands from the game were used in operations by the characters.
In the sitcom The Big Bang Theory, the character Sheldon Cooper loves Zork: in the episode "The Hofstadter Isotope" (S2E20), he mentions it as the game they are going to play on Friday "Chinese and vintage video game" night; in episode "The Toast Derivation" (S4E17), he proposes to play Zork in the small party that he organized.
- 69105, a number that became somewhat of an in-joke in several Infocom games
- Grue, the infamous Zork monster
- Tim Anderson (Winter 1985), "The History of Zork – First in a series", The New Zork Times, 4 (1): 7–11, archived from the original (PDF) on 2006-04-27
- "Dave Lebling on the Genesis of the Adventure Game - and the Creation of Zork", US Gamer, August 2014
- "The making of Zorkl", Retro Gamer, Imagine Publishing (77): 32–33, May 2010
- Tim Anderson (Spring 1985), "The History of Zork – Second in a series", The New Zork Times, 4 (3): 4–5, archived from the original (PDF) on 2006-04-27
- Liddil, Bob (February 1981). "Zork, The Great Underground Empire". BYTE. 6 (2). pp. 262–264. Retrieved 18 October 2013.
- Dave Lebling & Marc Blank (1984), Zork Trilogy Instruction Manual. (PDF), Infocom
- Maher, Jimmy (2012-01-18). "Exploring Zork, Part 1". The Digital Antiquarian. Retrieved 21 December 2014.
- Maher, Jimmy (2012-01-20). "Exploring Zork, Part 2". The Digital Antiquarian. Retrieved 21 December 2014.
- Maher, Jimmy (2012-01-22). "Exploring Zork, Part 3". The Digital Antiquarian. Retrieved 21 December 2014.
- "Infocom Scoreboard" (PDF), The New Zork Times, 3 (2): 3, Spring 1984
- "Hot Gossip". Computer Games. February 1985. p. 8. Retrieved 15 January 2015.
- Haha, Jimmy (2009-02-22). "Zork I Walkthrough" (Text file). Retrieved 2016-08-04.
- Dyer, Richard (1984-05-06). "Masters of the Game". The Boston Globe. Archived from the original on 1997-06-07.
- Lebling, P David (December 1980), "Zork and the Future of Computerized Fantasy Simulations", BYTE, 5 (12): 172–182
- Adams, Rick. "Here's where it all began...".
- Barton, Matt (28 June 2007). "The History Of Zork". Gamasutra.
- Tim Anderson (Spring 1985), "The History of Zork – Second in a series", The New Zork Times, 4 (2): 3–5, archived from the original (PDF) on 2006-04-27
- "Zork: A Computerized Fantasy Simulation Game", IEEE Computer, 12 (4): 51–59, April 1979, doi:10.1109/mc.1979.1658697
- Briceno, Hector; Wesley Chao; Andrew Glenn; Stanley Hu; Ashwin Krishnamurthy; Bruce Tsuchida (2000-12-15). "Down From the Top of Its Game: The Story of Infocom, Inc.". Retrieved 2007-06-07.
- Michael Feir (2007). "Zork Turns 30". Archived from the original on 2006-04-27.
In the brief time that Zork was known as Dungeon, the Fortran version of Dungeon was widely circulated which caused the name Dungeon to stick in some circles and sectors to this day.
- Roger Firth (2002). "InfLight – Inform debugging".
The result, around 1978, was Dungeon, (from which Bob Supnik at DEC created a Fortran version); the MDL original, however, was soon renamed Zork.
- Peter Scheyen (1996). "Dungeon". Archived from the original on 2006-06-17.
Version FORTRAN IV Zork (Dungeon) Release Date January 1978 Authors A somewhat paranoid DEC engineer
- Stanton, Jeffrey; Wells, Robert P.; Rochowansky, Sandra; Mellid, Michael, eds. (1984). The Addison-Wesley Book of Atari Software. Addison-Wesley. pp. 30–31. ISBN 0-201-16454-X.
- "The Infocom Gallery". elsewhere.org.
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- The DUNGEON (Zork I) source on github.com/devshane/zork
- dungeon-3.2A.tar.Z (05-Oct-1994) on the Interactive Fiction Archive "Dungeon version 3.2A, 1-Oct-94; contains all the rooms and puzzles of the original MIT Zork. DEC FORTRAN source code by Robert M. Supnik; see dungn32b.zip for a port to DOS."
- "The Infocom Gallery - Zork I". elsewhere.org.
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- "PORK I: The Great Underground Sewer System (1991)". archive.org.
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- Cline, Ernest. Ready Player One. Broadway Books, 2011, E-book edition, p. 1165.
- "Chuck Pilot".
Chuck: Yeah, if I could only I could remember what was in my hero's satchel... (Morgan looks at him quizzically) The weapons I would use to kill the Terrible Troll.
- Montfort, Nick. Twisty Little Passages. MIT Press, 2003. ISBN 0-262-13436-5.
- Download and play the original mainframe version of Zork – binaries for DOS (runnable under 32-bit Windows), Mac OS X and Linux, as well as a 1982 map of the Zork universe.
- Zork Trilogy at MobyGames
- Zork sites at DMOZ
- Feature on text adventures including Zork at The Dot Eaters at the Wayback Machine (archived May 14, 2013)
- "The History of Zork", an article by Matt Barton on Gamasutra
- Zork, Zork II, Zork III reviews of Commodore 64 (disk edition) in Zzap64, August 1985
- Zork I can be played for free in the browser at the Internet Archive
- Zork II can be played for free in the browser at the Internet Archive
- Zork III can be played for free in the browser at the Internet Archive