Gomoku

Lore & Background

Historical records indicate that gomoku originated in the mid-1700s during the Edo period in Japan. It is said that the 10th generation of Kuwanaya Buemon, a merchant who frequented the Nijō family, was highly skilled in this game, which subsequently spread among the people. By the late Edo period, around 1850, books had been published on gomoku. The earliest verified published book is the Gomoku Jōseki Collection in 1858.

The name 'gomoku' comes from Japanese: go means five, moku is a counter word for pieces, and narabe means line-up. In China it is called Wuziqi, and in Korea omok. In the nineteenth century, the game was introduced to Britain as Go Bang, derived from the Japanese word goban. It gained some popularity, and in the 1920s it was produced commercially by companies such as The Chad Valley Co Ltd in a modified version marketed as Spoil Five.

Gomoku has a strong advantage for the first player when unrestricted. Tournament play has adopted various opening rules to balance this, including the Pro rule (introduced later than 1989 and 1991 world championships) and the Swap2 opening protocol (adopted in 2009, reducing first-player win ratio to about 52 percent). Variants include Freestyle gomoku, Renju, Caro, Omok, Ninuki-renju, and Pente.

Reader's Guide

Gomoku is significant as a classic abstract strategy game with a long history and widespread cultural reach across East Asia and beyond. Its simple rules—players alternate placing stones to form an unbroken line of five—belies deep strategic complexity, particularly due to the strong first-player advantage. This imbalance has driven the development of numerous tournament opening rules and variants, such as Renju (which restricts black's moves with three-and-three, four-and-four, and overline rules) and Caro (which requires an unblocked five). The game's theoretical generalization into m,n,k-games and Connect(m,n,k,p,q) games shows its influence on game theory and combinatorial game design. The Swap2 opening protocol, adopted for world championships since 2009, has largely evened out the first-player advantage, making gomoku a more balanced competitive game. Its legacy includes commercial adaptations like Spoil Five in the 1920s and continued popularity in China, Korea, and Japan under various names.

Did You Know?

• Gomoku is traditionally played on a 15×15 board, though a 19×19 board was standard in the past.
• The earliest verified book on gomoku is the Gomoku Jōseki Collection from 1858.
• In the 1920s, The Chad Valley Co Ltd produced a modified version of gomoku marketed as Spoil Five.
• The Swap2 opening protocol, adopted in 2009, reduced the first-player win ratio to about 52 percent.