How to Play Gomoku

What Is Gomoku?

Gomoku is a two-player strategy board game in which players take turns placing stones on a grid. The first player to form an unbroken line of five stones in any direction — horizontal, vertical, or diagonal — wins the game. The name "Gomoku" comes from the Japanese word for "five pieces."

Gomoku has been played in East Asia for centuries and is closely related to the ancient game of Go, sharing the same board and stones. Despite having very simple rules, the game rewards deep strategic thinking. You can learn the rules in minutes, but mastering it takes practice. On sotjun.com, you can play against an AI opponent in your browser at any time.

What You Need

Traditional Gomoku is played on a 15×15 or 19×19 grid, with one player using black stones and the other using white. On sotjun.com, the board is ready as soon as you open the page — no setup required. You play as black, the AI plays as white, and black always goes first.

The Rules

• Players alternate turns, placing one stone per turn on any empty intersection of the grid.
• Once placed, a stone cannot be moved or removed.
• The goal is to connect five of your stones in a straight line — horizontally, vertically, or diagonally.
• In standard (free-style) Gomoku, a line of six or more also counts as a win.

Winning the Game

The moment you place a stone that completes a row of exactly five (or more, in free-style rules) consecutive stones of your color, you win. The winning line can run in any of four directions: left-right, up-down, top-left to bottom-right, or top-right to bottom-left.

Blocking your opponent is just as important as building your own line. If your opponent has four stones in a row with an open end, you must block immediately — otherwise they will complete five on the very next move. Recognizing these threats early is one of the most critical skills in Gomoku.

Your First Few Moves

A good opening move is to place your first stone near the center of the board. The center gives you access to all four diagonal and orthogonal directions, providing maximum flexibility for both attacking and defending. Placing stones near the edges early on severely limits your options.

In your first few turns, focus on building a connected group of two or three stones while also watching what your opponent is doing. Beginners often lose by focusing entirely on their own attack and missing that the opponent is one move away from winning.

Key Concepts to Know

Open three: Three consecutive stones with both ends unblocked. An open three is a strong threat because the opponent must block at least one end — and if two open threes exist simultaneously, only one can be blocked.

Four-in-a-row (four): Four consecutive stones. A four forces the opponent to block immediately. Creating two fours at the same time (double four) is a winning strategy because only one can be blocked.

Double three (3-3): A move that creates two open threes simultaneously. This is extremely powerful and very hard to defend against, making it a key intermediate technique.

Good Habits for Beginners

Before placing each stone, quickly check whether your opponent has any three-in-a-row or four-in-a-row threats. If they do, deal with the most urgent threat first. Ideally, your defensive move should also help build your own attack — look for intersections where a single stone both blocks the opponent and extends your own line.

As you gain experience, you will naturally start reading two or three moves ahead. This habit — called "reading" — is what separates intermediate players from beginners, and it improves rapidly with practice.