Editing Gomoku (section)

== First-player advantage ==
Gomoku has a strong advantage for the first player when unrestricted.<ref name=":1">{{Cite web|title=BoardGameGeek|url=https://boardgamegeek.com/thread/969642/article/36840025#36840025|url-status=live|archive-url=https://web.archive.org/web/20210722164845if_/https://boardgamegeek.com/thread/969642/article/36840025|archive-date=2021-07-22|access-date=2021-01-26|website=boardgamegeek.com}}</ref><ref name=":2">{{Cite web|title=Game database {{!}} GomokuWorld.com|url=http://gomokuworld.com/gamedatabase|access-date=2021-01-26|website=gomokuworld.com}}</ref>

Championships in gomoku previously used the "[[#Pro|'''Pro''']]" opening rule, which mandated that the first player place the first stone in the center of the board. The second player's stone placement was unrestricted. The first player's second stone had to be placed at least three intersections away from the first player's first stone. This rule was used in the 1989 and 1991 world championships.<ref name=":5" /> When the win–loss ratio of these two championships was calculated, the first player (black) won 67 percent of games.

This was deemed too unbalanced for tournament play, so tournament gomoku adopted the [[#Swap2|Swap2]] opening protocol in 2009. In Swap2, the first player places three stones, two black and one white, on the board. The second player then selects one of three options: play as black, play as white and place another white stone, or place two more stones, one white and one black, and let the first player choose the color.<ref name=":9">{{Cite web|title=Gomoku - swap2 rule|url=https://www.renju.net/rule/11/|access-date=2016-11-09|website=renju.net}}</ref><ref name=":4" />

The win ratio of the first player has been calculated to be around 52 percent using the Swap2 opening protocol, greatly balancing the game and largely evening out the first-player advantage.<ref name=":1" /><ref name=":2" /><ref name=":3">{{Cite web|title=History {{!}} GomokuWorld.com|url=http://gomokuworld.com/worldchampionship/6|url-status=live|archive-url=https://archive.today/20210707172514/http://gomokuworld.com/worldchampionship/6|archive-date=2021-07-07|access-date=2021-01-26|website=gomokuworld.com}}</ref>