pedit5, alternately called The Dungeon is a 1975 dungeon crawl video game developed for the PLATO system by Rusty Rutherford. It is considered to be the first example of a dungeon crawl game.
In the game, the player guides a character who wanders a single-level dungeon accumulating treasure and killing monsters. When a player encounters a monster, he can use one of several spells. Characters can be saved from one play session to the next. The dungeon was rendered using on-screen character graphics. Though the dungeon presents a fixed layout, the monster encounters and treasure were randomly generated, making it an early predecessor of the roguelike genre.
Source: Wikipedia, "Pedit5", available under the CC-BY-SA License.
Historical Context
While pedit5 appears to be the first dungeon crawl computer game, it was deleted just a few months after it was created. A second dungeon crawl game, m199h, was created in a lesson unit (i.e., space on a fixed drive) reserved for foreign language instruction. It was similarly deleted as soon as the illicit program was discovered. dnd, likely the third dungeon crawl game written for PLATO, had the most enduring success. It was the first PLATO lesson space created for the express purpose of being a dungeon game.
Later PLATO games, such as avatar, oubliette, baradur, moria, dndworld, bnd, and sorcery, were heavily influenced by dnd (and each other) while adding innovative features of their own, from 1976 to 1979. Dungeon games mentioned in this article can be played online through the Cyber1 system (a restoration of a mid-1980s vintage PLATO system).
Source: Wikipedia, "Dnd (video game)", available under the CC-BY-SA License.