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 in 1977–1979 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 in 1980, 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.  This was due to the size of the game and its inability to fit on floppy disks of the time.

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.

"Feelies" were not included until the 1984 "Grey box" re-release.