1 Introduction

Gomoku, also called Five in a Row (Chinese: "五子棋"，"五目", etc.), is an abstract strategy board game. It is traditionally played by two players with Go pieces (black and white stones) on a Go board.

It is played using a 15×15 board, while in the past a 19×19 board was standard. The game is known in several countries under different names.

Players alternate turns placing a stone of their color on an empty intersection. Black plays first. The winner is the first player to form an unbroken chain of five stones horizontally, vertically, or diagonally.

2 First Player Advantage

It has been proven that the first player can force a win, to mitigate this imbalance, professional games have adopted extra rules. Since 2009, championships have adopted the "swap2" opening rule.

3 Opening Rules

3.1 Pro

The Pro opening rule has been previously adopted in championships, but was dropped after being deemed too unbalanced.

The first player's first stone must be placed in the center of the board. The second player's first stone may be placed anywhere on the board. The first player's second stone must be placed at least three intersections away from the first stone (two empty intersections in between the two stones).

3.2 Swap2

The first player places three stones on the board, two black and one white. The second player then has three options:

  1. They can choose to play as black
  2. They can choose to play as white and place a second white stone
  3. Or they can place two more stones, one black and one white, and pass the choice of which color to play back to the first player.

Because the first player doesn't know where the second player will place the additional stones if they take option 2 or 3, the swap2 opening protocol limits excessive studying of a line by only one of the players.

4 Variants

4.1 Freestyle

4.2 Renju

It is played on a 15×15 board, with the rules of three and three, four and four, and overlines applied to Black only. Renju also makes use of various tournament opening rules, such as Soosõrv-8, the current international standard for this variant.

5 Rules