Zork

Zork is a text-based adventure game wherein the player explores the ruins of the Great Underground Empire. The player types text commands for their character to traverse locations, solve puzzles, and collect treasure. The game has hundreds of locations, each with a name and description, and the player's commands interact with the objects, obstacles, and creatures within them. , "put the lamp and sword in the case").

, "get lamp" works only if a lamp is present). The program acts as a narrator, describing to the player their location and the results of certain actions. If the game does not understand the player's commands, it asks for the player to retype their actions. The program's replies are typically in a sarcastic, conversational tone, much as a Game Master would use in leading players in a tabletop role-playing game.

Most of the setting is established through the game's written descriptions of items and locations, as well as manuals in later game releases. The game is set in a massive cave complex built by the Quendor Empire, which was eventually renamed to the Great Underground Empire by Lord Dimwit Flathead, who spent his reign building massive, largely pointless projects such as an underground dam and the royal museum. The empire's overspending caused it to collapse, and all the residents left. The abandoned empire is the setting of the three episodes of Zork.

Zork I begins with the unnamed player standing in an open field west of a white house. The house leads to an underground area where most of the game takes place. The player must find 19 treasures and store them in a trophy case. In Zork II, the player learns of the royal Flathead family, and meets the Wizard of Frobozz, a once-respected enchanter exiled by Lord Dimwit Flathead when his powers began to fade.

Tim Anderson, Marc Blank, Bruce Daniels, and Dave Lebling began developing Zork in May 1977. The four were members of the Dynamic Modelling Group, a computer science research division at the Massachusetts Institute of Technology (MIT) Laboratory for Computer Science—Anderson, Blank, and Daniels as students and Lebling as a research staff member. Their work was inspired by Colossal Cave Adventure, a text-based game that is the first well-known example of interactive fiction and the first well-known adventure game. Adventure was immensely popular among the small population of computer users of the time and a big hit at MIT in early 1977. By the end of May, players had managed to completely solve it.

The four programmers began to design a game that would be a "better" text adventure game, with inputs more complex than Adventure's two-word commands and puzzles less obtuse. They believed that their division's MDL programming language would be better suited for processing complex text inputs than the Fortran code used in Adventure. The group was familiar with creating video games: Blank and Anderson had worked on a multiplayer trivia game called Trivia (1976), and Lebling was heavily involved with Maze (1973), a multiplayer first-person shooter and the first 3D first-person game ever made. Lebling first created a natural language input system, or parser, that could process typed two-word instructions.

Following its 1980 release, Zork I became a bestseller from 1982 through 1985, with 380,000 copies sold by 1986. In its first nine months Personal Software sold 7,500 copies for the TRS-80 and Apple II. Sales ballooned as Infocom began self-publishing the trilogy and the personal computer market expanded. Zork I had sold 38,000 copies by the end of 1982, nearly 100,000 in 1983, and around 150,000 copies in 1984.

Its success outpaced Infocom's later games; Inc. reported in 1983 that Zork I, only one of Infocom's fifteen released titles, composed twenty percent of their annual sales. Zork I sales declined beginning in 1985. The second and third parts of Zork also sold well, though not as highly as the first: more than 170,000 Zork II and 130,000 Zork III copies sold by 1986.

Zork has been described as "by far the most famous piece of [interactive fiction]" and "the father figure of the genre". Game historian Matt Barton contended that "to say that Zork is an influential adventure game is like saying the Iliad is an influential poem". Rather than simply influencing games, Barton said it instead showed that the computer could simulate a rich virtual world, and helped lay the foundations of video game concepts around exploring, collecting objects, and overcoming problems. Nick Montfort, in his book on interactive fiction Twisty Little Passages: An Approach to Interactive Fiction (2003), suggested that Zork's legacy and influence lay not in its parser or writing, but in the way it modeled the game world as a complex, dynamic space that the player moved through.

Janet Murray, in Hamlet on the Holodeck (1997), considered this a result of the way the game was programmed compared to other games of the time, with each area, item, and actor modeled as their own object that could act and be acted upon. Historians have argued that Zork, along with Colossal Cave Adventure, influenced the creation of the MUD genre, and through it the more recent massively multiplayer online role-playing game genre.