Gomoku

Overview

Gomoku, also known as Five in a Row or Wu Zi Qi (五子棋), is a strategic board game played on a grid with black and white pieces. The objective is to be the first player to form a continuous line of five pieces either horizontally, vertically, or diagonally. While simple to learn, Gomoku offers significant strategic depth, making it popular across East Asia and beyond.

The game has various international names including Gomoku (Japanese "gomoku" meaning "five points"), Gobang, Connect 5, and Piskvorky (Czech). Different cultures have developed their own variations and rulesets to address the inherent advantage of the first player, leading to distinct game forms such as Renju (Japanese professional variant) and modern Gomoku with swap rules.

History

Development

The exact origins of Gomoku remain unclear in historical records, but it is traditionally believed to have been played in China before the invention of Go (围棋). During the Northern and Southern Dynasties period, the game spread to Goryeo (modern Korea) and subsequently to Japan.

Initially popular among Japanese nobility, Gomoku became widely played among common people by the end of the Genroku era (1688-1703). In 1899 (Meiji 3), the newspaper "Manichi Shimbun" officially named the game "Renju" (連珠), inspired by a passage from the "Book of Han" describing "the sun and moon as if joined together, and the five planets as if connected with pearls."

In the early 20th century, traditional Gomoku and Renju were introduced to Europe. The game was translated as "Five In a Row" (abbreviated as FIR), while "Gomoku" and "Gobang" were derived from Japanese romanizations, and "Renju" became the standard term for the professional variant.

In 1958 and 1979, Sweden and the Soviet Union established Renju federations respectively. In 1988, the Renju International Federation (RIF) was founded in Sweden, uniting organizations from Japan, the Soviet Union, and Sweden. In the 1990s, European countries introduced "swap" rules to traditional Gomoku, leading to the development of new Gomoku variants. Central European countries formed Gomoku organizations and established the International Federation (GCIF) alongside Six-in-a-Row. In August 2009, the 11th World Renju Championship and 3rd World Gomoku Championship were held in Pardubice, Czech Republic.

Since the beginning of the 21st century, World Renju Championships, World Gomoku Championships (GT), and Six-in-a-Row International Open Tournaments (CT) have been held concurrently.

In China, the General Administration of Sport of China approved the Chinese Chess Academy to organize national Gomoku competitions in 2001. The first National Gomoku Individual Invitational Tournament was held in August 2002. In 2003, the General Administration of Sport approved the "Chinese Gomoku Competition Rules" and the "Chinese Gomoku Dan and Kyu System" for trial implementation. In February 2006, Gomoku was officially established as a secondary project under Go, and new Gomoku clubs were established across the country.

Reforms

Addressing the "First Player Advantage"

As Gomoku developed, it became apparent that the first player holds a significant advantage, leading to the conclusion that "first player wins" with optimal play. For Gomoku to become a competitive sport, the core issue was solving this "first player advantage" problem in traditional play.

"Competitive Gomoku" refers to an intellectual competitive sport where two players compete using a board and pieces.

"Swap" Strategy

The "swap" strategy can be metaphorically described as "one person cuts the cake, the other chooses which piece to take." In this method, one player opens the game, and the other chooses to play as black or white. This approach is fair, efficient, and practical. However, it transforms the game into a strategic opening choice rather than pure skill, while "winning openings" still exist.

Examples include Europe's Swap2 and Swap1, and China's Swap3 and one-hand swap rules.

"Forbidden Moves" Concept

This approach prohibits certain winning tactics to balance the advantage between first and second players. Japanese Renju introduced "forbidden moves" to weaken the first player's advantage. However, subsequent development of Renju showed that forbidden moves couldn't fully balance the gap between first and second players, and "first player wins" remained the outcome.

"Foam" Principle

Similar to bubbles that can burst, this principle is exemplified in "capture" Gomoku, where forming five in a row causes those pieces to disappear while removing one opponent's piece and adding one of your own. This changes Gomoku from a "golden goal" system to a "scoring" system, maximizing board and piece utilization and introducing new strategic thinking. The challenge lies in calculating the winner.

"Tic-Tac-Toe" Principle

Also known as Noughts and Crosses, Tic-Tac-Toe is a draw due to limited space. Reducing the board size can suppress the first player's advantage in Gomoku, such as using 15x15, 13x13, or smaller boards. The question becomes: what board size results in a draw, and can such a variant remain a competitive sport?

"Seesaw" Principle

In traditional Gomoku, the first player always leads by one piece. What if both players alternately led by one piece? This principle is exemplified by Six-in-a-Row, invented by a Taiwanese professor. The first player places one piece, then both players alternately place two pieces, with the first to form six in a row winning. Six-in-a-Row was included in the 11th Olympiad of Computer Games, verifying its fairness and complexity.

"Renju" Principle

Combining "forbidden moves," "swap" strategy, and the "tic-tac-toe" principle results in Renju. Examples include RIF rules, Sakata rules, Yamaguchi rules, and Tarannikov rules.

Key Information

Cultural Significance

Different cultures have developed unique nicknames for Gomoku that reflect their perception of the game. In Korea, it's called "couple's chess," suggesting that playing the game between lovers enhances emotional communication. Europeans refer to it as "gentleman's chess," representing the refined etiquette displayed during play. The Japanese call it "middle-aged and elderly chess," indicating that the game suits the physical and thinking patterns of this demographic.

In China, Gomoku has been recognized as an official mind sport. The inclusion of Gomoku in the National Intellectual Games in 2009 marked its formal recognition as a competitive sport in the country. The game's accessibility—requiring only a board and pieces—has contributed to its widespread popularity across different social strata in China.

Modern Status

Today, Gomoku, Six-in-a-Row, and Renju have become integral components of modern European Gomoku, with numerous tournaments of varying scales held regularly. World Championships for all three variants are now conducted concurrently.

In China, the "Chinese Gomoku Competition Rules" (2003 edition) references RIF rules while also accommodating traditional Gomoku play. The Chinese Gomoku Dan and Kyu system has been established to recognize player skill levels, with tournaments held at both national and international levels.

The game continues to evolve with new strategic developments and rule variations. Computer programming has also contributed to Gomoku's development, with strong AI programs capable of challenging top human players and opening new avenues for strategic analysis.

Rules

1. Two players each use pieces of one color (traditionally black and white).
2. The game starts with an empty board.
3. Black moves first, followed by white, with players alternating turns.
4. Each player places one piece at a time on an empty intersection point of the board.
5. Once placed, pieces cannot be moved or removed.
6. The first player to form an unbroken line of five pieces horizontally, vertically, or diagonally wins.

In competitive Gomoku (Renju), additional rules apply to balance the first player advantage:
- Black's first move must be in the center (H8).
- After black's third move, white may choose to swap colors.
- After black's fifth move, white may place two stones, and black chooses one to keep.
- Black is forbidden from making "double three," "double four," or "overline" (six or more in a row) moves, while white has no restrictions.

Terminology

Game Terms

• Black/White: The player using black/white pieces.
• Open Point: An empty intersection where a piece can be placed.
• Line: A row of pieces of the same color.
• Five: Five pieces in a row (winning condition).
• Overline: Six or more pieces in a row (typically a loss for black in Renju).
• Open Four: Four pieces with both ends open to potentially form five.
• Double Three: Creating two separate open threes simultaneously (forbidden for black in Renju).
• Double Four: Creating two separate fours simultaneously (forbidden for black in Renju).

Strategic Terms

• VCF: Victory by Continuous Four - winning by creating a series of forced four-in-a-row moves.
• VCT: Victory by Continuous Threat - winning through a series of threats.
• Windmill: A pattern where threats are created in a circular fashion.
• Two-headed Snake: A pattern where both ends of a three contain threats.
• Forbidden Point: A position where black would be forced to make an illegal move.

Techniques

The Five Elements of Gomoku Strategy

Chinese Gomoku pioneer Na Wei (九段) developed a strategic framework known as "Na's Five Elements of Gomoku Strategy":

1. Attack when having the initiative, defend when responding. Attack to defend, defend to attack.
2. Switch between attack and defense carefully.争夺 the initiative at the beginning.
3. Defense takes the outer position, attack concentrates inner strength. The Bagua formation is easy to defend, forming corners is easy to attack.
4. Block and separate, stand firm as a mountain. Without striving to be first, victory is as difficult as ascending to heaven.
5. In the opening, compete for two-point formations; in the endgame, compete for three-point formations. Keeping three without rushing creates countless variations.

Basic Tactics

One of the most common winning methods is "one stone double kill"—placing a single stone that creates two simultaneous threats that the opponent cannot both block. This technique has numerous basic patterns depending on the board configuration.

Opening Patterns

The opening (or "formation") in Gomoku typically occurs within the first 3-7 moves and is crucial to the game's outcome. In competitive play, 26 standard openings are recognized, each with a poetic name:

• Direct Openings: Cold Star, Stream Moon, Scattered Star, Flower Moon, Waning Moon, Rain Moon, Metal Star, Pine Moon, Hill Moon, New Moon, Auspicious Star, Mountain Moon, Wandering Star
• Slant Openings: Long Star, Narrow Moon, Fixed Star, Water Moon, Meteor, Cloud Moon, Shore Moon, Storm Moon, Silver Moon, Bright Star, Slant Moon, Famous Moon, Comet

These openings are memorized using the "Peng's Mnemonic":

Twenty-six openings first abandon two, direct wandering star slant comet. Black must lose opening.
Cold star stream moon scattered star first, flower waning two moon and white lotus,
Rain moon metal star chase black jade, pine hill new night auspicious mountain bloody.
Star moon long narrow fixed water flow, white lotus drooping cloud shore storm,
Black jade silver moon leaning bright star, slant moon famous moon can be called friends.

References

1. 中国棋院. (2009). 《中国五子棋竞赛规则》. 人民体育出版社.
2. Salo, T., & Westerinen, U. (2003). Renju: The Art of Five in a Row. Finnish Renju Federation.
3. 中国五子棋运动协会. (2015). 《五子棋基础教程》. 蜀蓉棋艺出版社.
4. Lin, H. X., & Wu, D. (2008). Gomoku and Renju: Theory and Practice. Hebei Education Press.
5. Renju International Federation. (2022). Renju Rules and Tournament Guidelines.