[From Wikipedia: http://en.wikipedia.org/wiki/Mystery_House] Mystery House is an adventure computer game released in 1980 by Roberta and Ken Williams for the Apple II. The game is remembered as one of the first adventure games to feature computer graphics and the first game produced by On-Line Systems, the company which would evolve into Sierra On-Line. Because of its use of graphics, GamePro named Mystery House the 51st most important game of all time in 2007.