Rules of Go

Go is an ancientboard gamethat requires strategic, observation and tactical skills. It emerged in China more than 2,500 years ago and was considered one of the four essential arts in ancient China. Despite the simplicity of its rules, Go is famous for being one of the most complex games in the world.

Number of players

The game is designed for two players.

Aim of the game

The goal is to control more territory than the opponent. As the game progresses, each player places stones on the board, trying to form and expand their territory. These territories are disputed in a complex fight between the black and white stones, which may result in the expansion, reduction or even loss of the territory in question.

Board, Stones and Bowls

The game takes place on a board with a grid of 19 vertical and 19 horizontal lines, creating 361 intersections. Beginners often use smaller boards, 13x13 or 9x9, without modifying the rules of the game. The intersections 4D, 4J, 4P, 10D, 10P, 16D, 16J and 16P are known as hoshi (stars). The central intersection, 10J, is named tengen (origin of the sky).

A complete set of stones usually consists of 181 black and 180 white pieces, enough to cover the entire board, with an additional black stone as the player using them makes the first move. There are two main types of stones: convex, with one flat side and a curved one, and biconvex, with both sides curved.

The bowls for the Go stones have an oblate spherical shape. Generally, the lid is turned over at the beginning of each game to place the stones captured during the game in it.

Gameplay

At the beginning of the game the board is empty, and the player with the black stones makes the first move. From there, both players alternate. Each move in the game consists of placing a new stone at an empty intersection on the board, without moving the already placed stones.

Liberties and territory

To understand the dynamics and the objective of the game, it is important to define two key concepts:

• Empty intersections adjacent to a stone or group of stones are called liberties.
• Free intersections that are completely surrounded by stones of a single colour are considered the territory of the player controlling that colour, and are called eyes.

Capture of the stones

A group of stones is captured when it loses all its liberties, that is, when it is completely surrounded by stones of the opposing player, without any free space inside.

When a player makes a move that leaves an opponent's stone or group of stones without liberties, they must remove those surrounded stones from the board and keep them aside until the end of the game. The stones or formations that are left with only one liberty, and that can therefore be captured in the next movement, are called atari. The captured stones, called prisoners, are important because they are accounted for when calculating the score at the end of the game.

Limitations when placing stones

• Suicide: It is not allowed to place a stone in an intersection where it would be left without liberties, unless this move captures enemy stones.
• The ko rule: A situation called ko is a situation in which white and black stones can capture each other indefinitely, which would result in an infinite repetition of the same position on the board and no advancement in the game. To avoid this infinite cycle, the ko rule applies. It stipulates that if a player captures a stone in a ko situation, the opponent cannot recapture immediately. First he must make a different move and then he can try the recapture.

Life or death

When a group of stones is almost surrounded and has no options to connect with other friendly stones, the status of such a group is alive, dead or unstable. A group of stones is said to be alive if it cannot be captured, even if the opponent moves first. Conversely, a group of stones is said to be dead if it cannot avoid being captured. In any other case, the group is said to be unstable: in such a situation, the player who moves first might be able to make the group live (if it´s their own), or to kill it (if it´s the opponent's).

For a group of stones to survive, it must be able to create at least two eyes. This ensures that the group always maintains at least two liberties and therefore cannot be captured by the opponent. A single eye is not enough to ensure survival, since a point that would normally be forbidden by the suicide rule can be occupied if the stones that form the eye are completely surrounded by enemy stones.

Seki (mutual life)

There is an exception to the requirement that a group must have two eyes to survive, known as seki or mutual life. This situation occurs when two opposing groups are adjacent and share liberties, creating a position where neither player wants to move first, as doing so would allow the opponent to capture their group. Under these circumstances, the stones of both players remain on the board in a state of mutual life, or seki. Although no player receives points for these groups, both groups are kept alive instead of being captured.

End of match

The game ends when both players agree that it is not possible to gain more territory, capture enemy stones or reduce the opponent's territory. In such a case, the player passes their turn instead of placing a stone on the board. When both players pass consecutively, the end of the game is declared.

At the end of the game, the players identify the stones that would inevitably be captured if the game continued. These are known as dead stones, and they are captured before the score is evaluated.

Scoring

There are two main methods for counting points:

• Chinese Rules: Each player receives one point for each stone of their own colour that remains on the board, in addition to one point for each empty intersection within their territory. The player with the highest score wins. In case of a draw, the victory is awarded to White as compensation for having played after the first move of Black.
• Japanese Rules: Each player receives one point for each empty intersection within their territory, plus one point for each stone captured from the enemy. Whoever gets the highest score wins. In the event of a draw, White would win in compensation for having started the game after Black.

Komi

As in many games, the player who starts has a certain advantage. To balance this advantage, the score is adjusted by awarding a number of points to the opponent, known as komi. The value of komi is adjusted according to the rules used, the size of the board and statistical analysis of games played by experienced players. It is usually a decimal number to avoid a draw, and is usually around 6 points.

Strategies

The general strategy in Go focuses on expanding one's territory whenever possible, attacking the opponent's weak points (groups that could be eliminated) and always maintaining awareness of the “state of life” of one's own groups. Situations in which two opposing groups must capture each other in order to survive are known as a “capture race”. In a capture race, the group with the most liberties and/or the best formation will be the one that finally manages to capture the opponent's stones. These capture races and the issues of life and death reflect the complexity and challenges inherent in Go.

Conquer the board, challenge your mind and experience the satisfaction of every move in an eternal dance of strategy and skill!