By Galo S Mirth
Bonanza was one of the decisive turning points in computer shogi. Built by Kunihito Hoki, it was not just another strong engine. It changed how developers thought about search, evaluation, and data driven tuning. In Japan, people later called its training approach the Bonanza Method, and by the early 2010s that approach had spread across the top tier of tournament engines.
This article looks at Bonanza’s origin, its major milestones, its famous encounters with professional shogi, and why its influence lasted far beyond one program.
Origin story: a chemist in Canada builds a shogi engine
According to Japanese sources, Hoki developed Bonanza while living in Canada as a researcher, and version 1.0 was released in June 2005. One reason Bonanza drew attention so quickly was the unusual background of its author. Hoki was a physical chemist, not a traditional shogi software insider. He has said he adapted ideas from computer chess and from optimization thinking connected to his scientific research.
That outsider perspective mattered. Bonanza challenged assumptions that had become common in computer shogi development during the early 2000s.
The 2006 shock: first appearance, immediate WCSC title
At the 16th World Computer Shogi Championship in 2006, Bonanza won on its first appearance. The Computer Shogi Association records Bonanza as champion that year. In context, this was a major upset. Established names such as YSS, KCC Shogi, and Gekisashi had dominated previous years, so a new engine winning immediately was a landmark moment.
Bonanza and pro shogi: the Watanabe exhibition match
In March 2007, Bonanza played an exhibition game against then Ryuo Akira Watanabe. Watanabe won, but the game became historically important because it showed how close top software was getting to elite human play in serious time controls. Japanese coverage and later retrospectives repeatedly treat this match as a symbolic checkpoint in the computer shogi timeline.
What the Bonanza Method changed
Bonanza’s strongest long term impact was methodological. Japanese sources describe two connected points. First, Bonanza aggressively used broad search in positions where earlier software often relied more heavily on selective pruning assumptions. Second, it tuned large evaluation parameters from game records instead of hand tuning everything by expert intuition. The term Bonanza Method came to describe this data driven parameter optimization style.
When Hoki released key algorithm details and later opened the core source, this accelerated adoption. Rival teams could study, adapt, and extend the ideas, and the center of gravity in computer shogi shifted quickly.
Milestones after the breakthrough
- 2005: Bonanza v1.0 released.
- 2006: WCSC 16 champion (first appearance).
- 2009: major source release enabled broad reuse.
- 2011: Bonanza runner-up at WCSC 21.
- 2013: Bonanza won WCSC 23, a second world title.
Even when Bonanza itself was not the champion, many teams were already using Bonanza lineage techniques. That is the clearest sign of influence: the field began to look more like Bonanza’s design philosophy.
Legacy in the computer shogi vs pro era
Bonanza sits at the center of the transition period that led into the later computer vs professional era, including the stronger clustered systems and multi engine combinations that appeared around Denosen years. It did not single handedly create every later breakthrough, but it supplied a practical blueprint that many teams could build on.
In short, Bonanza mattered because it won, because it was transparent enough to teach others, and because it pushed computer shogi toward modern machine tuned evaluation design.
Sources (Japanese)
- Japanese Wikipedia, 「Bonanza」 (oldid=106839765): https://ja.wikipedia.org/w/index.php?title=Bonanza&oldid=106839765
- Japanese Wikipedia, 「保木邦仁」 (oldid=104321222): https://ja.wikipedia.org/w/index.php?title=%E4%BF%9D%E6%9C%A8%E9%82%A6%E4%BB%81&oldid=104321222
- Japanese Wikipedia, 「世界コンピュータ将棋選手権」 (oldid=106966325): https://ja.wikipedia.org/w/index.php?title=%E4%B8%96%E7%95%8C%E3%82%B3%E3%83%B3%E3%83%94%E3%83%A5%E3%83%BC%E3%82%BF%E5%B0%86%E6%A3%8B%E9%81%B8%E6%89%8B%E6%A8%A9&oldid=106966325
- コンピュータ将棋協会, 「世界コンピュータ将棋選手権」一覧: https://www.computer-shogi.org/wcsc/