Coulom began writing Crazy Stone in July 2005, and at the outset incorporated the Monte Carlo algorithm in its design. Early versions were initially available to download as freeware from his website, albeit no longer. Pattern recognition and searching was added in 2006, and later that year Crazy Stone took part in its first tournament, winning a gold medal in the 9×9 competition at the
11th Computer Olympiad. In March 2013, Crazy Stone beat
Yoshio Ishida, Japanese 9-dan former
Honinbo Meijin, in a 19×19 game with four handicap stones. On March 21, 2014, at the second annual Densei-sen competition, Crazy Stone defeated
Norimoto Yoda, Japanese professional 9-dan, in a 19×19 game with four handicap stones by a margin of 2.5 points. ==Performance==