Gomoku

Gomoku is a two-player placement game where you try to line up five stones in a row before your opponent does. It grew up on Go boards in Japan during the Edo period (1603 to 1868), where it was called Gomoku Narabe, meaning five points in a row. The earliest verified book on the game, the Gomoku Joseki Collection, appeared in 1856. In 1899 the Tokyo Renju Club formalized the restricted variant called Renju to fix Black's huge first-move advantage. Computer scientist L. Victor Allis proved in 1994 that freestyle Gomoku is a forced win for the first player with perfect play, a result that explains why tournament Renju adds special rules for Black. A 2021 study in NeuroImage linked abstract board-game play to stronger activity in the prefrontal cortex during planning tasks. Place your first stone and start reading the board.

1. Black moves first. Click any empty intersection on the 15x15 grid to place your stone.
2. Players alternate placing one stone per turn on any empty intersection. Stones do not move once placed.
3. Connect five of your stones in a row, horizontally, vertically, or diagonally, to win.
4. There is no gravity. You can place a stone anywhere on the board, unlike Connect Four.
5. Block your opponent's open fours immediately. An open four wins on the next move no matter where the defender plays.
6. Choose a difficulty level or switch to 1v1 to play a friend on the same device.

• The board is a 15x15 grid of intersections. Black always plays first.
• Each turn, a player places one stone on any empty intersection.
• Stones are never moved or captured. The board only fills up.
• The first player to align exactly five stones in a straight line wins. Horizontal, vertical, and diagonal lines all count.
• In freestyle rules, a line of six or more also wins. In strict Renju rules, an overline of six or more is a foul for Black.
• If the board fills with no five-in-a-row, the game is a draw.

• Build open threes. An open three (a line of three with both ends free) becomes an open four on your next turn, which is unstoppable. Your opponent must respond immediately.
• Create double threats. A single stone that simultaneously extends two open threes forces the defender to block one while you win with the other.
• Control the center early. The middle of the 15x15 board reaches more lines in every direction, so central stones contribute to more potential fives.
• Watch for split fours. A four with a gap in the middle, such as X X _ X X, still wins next turn and is easy to miss. Scan every line before you move.
• Learn the Renju forbidden moves for Black. Double threes, double fours, and overlines are fouls for Black in tournament play, which is why those rules exist to balance the first-player edge.

• Renju: The tournament variant formalized in Japan in 1899. Black is forbidden from making double threes, double fours, or overlines, which removes the first-player forced win and creates a balanced game.
• Connect Six: Each turn a player places two stones instead of one, and the goal is six in a row. The two-stone move keeps the game closer than standard Gomoku despite the longer winning line.
• Go 9x9: Uses the same board and stones, but the goal is to surround territory and capture groups rather than line up five in a row.

• The rules take one minute to learn. The strategy takes years to master.
• No dice, no cards, no luck. The better reader wins.
• A full game lasts under 15 minutes, so you can play several in a row.
• The 15x15 board has room for creative shapes and sneaky double threats.

Play Gomoku in your browser with no download. Choose Easy, Medium, or Hard CPU, or switch to 1v1 and play a friend on the same device. Our version highlights winning lines, tracks moves, and lets you restart instantly. Place your first stone and go for five in a row.

Gomoku distills placement strategy into five stones in a row. Build open threes, fork with double threats, and block gap fours before they win. Play the CPU at three levels or challenge a friend locally. Place your first stone now.

• L. Victor Allis - A Knowledge-Based Approach to Connect-Four and Gomoku (1994)
• Renju International Federation - history and rules