Telengard is a computer-based video game that provides an early example of the dungeon crawl genre. The game, written in 1976 by Daniel Lawrence (1958–2010), was purchased by Avalon Hill in 1982 and made available on multiple computer platforms. These included the Commodore C64, the Apple II+, TRS-80, Atari 400 and Atari 800, and various IBM machines such as the IBM PCjr, and the IBM PC. Telengard is available on Windows and many ports and emulations are available for modern computers and operating systems.
Telengard, written from only 8 kilobytes of memory, offers no final solution for players. It simply provides a gaming platform for players to explore dungeons in real time. It has been referred to as a predecessor to Diablo, and is an early example of a roguelike video game.
Source: Wikipedia, "Telengard," available under the CC-BY-SA License.