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,[6] 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.
FrobozzCo International is a fictional monopolistic conglomerate from the game. FrobozzCo products are littered throughout all Zork games, often to humorous effect.
Several treasures and locations in Zork reveal that there used to be a large aristocratic family called the Flatheads, who reigned supreme over the GUE. The instruction manual to the Zork Trilogy tells the reader that there were twelve rulers from this family, referencing the book The Lives of the Twelve Flatheads. 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,[6] or else, if they continue 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 where a light source cannot be brought.
- Platform: MS-DOS