 Lawrence first wrote the game as "DND", a 1976 version of "Dungeons & Dragons" for the DECsystem-10 mainframe computer.He continued to develop "DND" at Purdue University as a hobby, rewrote the game for the Commodore PET 2001 after 1978, and ported it to Apple II+, TRS-80, and Atari 800 platforms before Avalon Hill found the game at a convention and licensed it for distribution.Its Commodore 64 release was the most popular.