In 1979 and 1980 Roberta and Ken Williams wrote Mystery House for the Apple II. Containing 70 simple two-dimensional drawings by Roberta Williams, Mystery House was the first computer adventure game with graphics. The game was also eventually released into the public domain.
♦ Later it was converted into an ap. In December 2013 you could buy version 1.0.6 of the program in the iTunes Store at this link.