Zork: The Great Underground Empire is a classic text adventure game. The player begins as an "adventurer" standing near a white house in a nice forest, but soon descends into the Great Underground Empire, where most of the game takes place. The player's quest is to collect the Nineteen Treasures of Zork.

As was typical for adventure games of its era, Zork does not use graphics. Instead, it communicates with the player via text, and the player interacts with the game by typing commands, such as "examine mailbox" or "take torch". For movement, the player types in geographical directions (such as "north" or "east" - or just "n" and "e"), and can check what items are being carried with the "inventory" command (or just "i").

The game was adapted from a larger mainframe version from the late 1970s, and is one of the first examples of its genre.