He was the producer of Activision's Ghostbusters, the game Hacker, the Atari and Commodore 64 versions of Pitfall II and Shanghai (the first commercial version of Brodie Lockard's Mahjong solitaire), and he designed and produced the first commercial version of computer solitaire (Solitaire Royale, published by Spectrum Holobyte).
Playing Mahjong solitaire optimally in the sense to maximize the probability of removing all tiles is PSPACE-complete, and the game gets NP-complete when peeking below tiles is allowed.
Examples of games that are PSPACE-complete (when generalized so that they can be played on an n × n board) are the games hex and Reversi and the solitaire games Rush Hour, Mahjong, Atomix, and Sokoban.
Mahjong | Mahjong solitaire | Solitaire Royale | mahjong | Cheating at Solitaire | World Mahjong Organization | Solitaire Townsend | Monte Carlo (solitaire) | Mahjong tiles | Mahjong (1996 film) | Japanese Mahjong yaku | ''Desert Solitaire'' |
Shisen-Sho (四川省), a Japanese tile-based game similar to Mahjong solitaire