Go (game)

The first 150 moves of a Go game animated. (Click on the board to restart the animation in a larger window.)

Aside from the order of play (alternating moves, Black moves first or takes a handicap) and scoring rules, there are essentially only two rules in Go:

Almost all other information about how the game is played is a heuristic, meaning it is learned information about how the game is played, rather than a rule. Other rules are specialized, as they come about through different rule-sets, but the above two rules cover almost all of any played game.

Except where noted, the basic rules presented here are valid independent of the scoring rules used. The scoring rules are explained separately. Go terms for which there is no ready English equivalent are commonly called by their Japanese names.

One black chain and two white chains, with their liberties marked with dots. Liberties are shared among all stones of a chain and can be counted. Here the black group has 5 liberties, while the two white chains have 4 liberties each.
If White plays at A, the black chain loses its last liberty. It is captured and removed from the board.

After both players have passed consecutively, the stones that are still on the board but unable to avoid capture, called dead stones, are removed.

Area scoring (including Chinese): A player's score is the number of stones that the player has on the board, plus the number of empty intersections surrounded by that player's stones.

If there is disagreement about which stones are dead, then under area scoring rules, the players simply resume play to resolve the matter. The score is computed using the position after the next time the players pass consecutively. Under territory scoring, the rules are considerably more complex; however, in practice, players generally play on, and, once the status of each stone has been determined, return to the position at the time the first two consecutive passes occurred and remove the dead stones. For further information, see Rules of Go.

An eye is an empty point or group of points surrounded by a group of stones. If the eye is surrounded by Black stones, White cannot play there unless such a play would take Black's last liberty and capture the Black stones. (Such a move is forbidden according to the suicide rule in most rule sets, but even if not forbidden, such a move would be a useless suicide of a White stone.)

Example of seki (mutual life). Neither Black nor White can play on the marked points without reducing their own liberties for those groups to one (self-atari).

A ladder. Black cannot escape unless the ladder connects to black stones further down the board that will intercept with the ladder or if one of white's pieces have only one liberty.

A net. The chain of three marked black stones cannot escape in any direction.

A simplified ko fight on a 9×9 board. The ko is at the point marked with a square—Black has "taken the ko" first. The ko fight determines the life of the A and B groups—only one survives and the other is captured. White may play C as a ko threat, and Black properly answers at D. White can then take the ko by playing at the square-marked point (capturing the one black stone). E is a possible ko threat for Black.

Strategy deals with global influence, interaction between distant stones, keeping the whole board in mind during local fights, and other issues that involve the overall game. It is therefore possible to allow a tactical loss when it confers a strategic advantage.

The strategy involved can become very abstract and complex. High-level players spend years improving their understanding of strategy, and a novice may play many hundreds of games against opponents before being able to win regularly.

Tournament and match rules deal with factors that may influence the game but are not part of the actual rules of play. Such rules may differ between events. Rules that influence the game include: the setting of compensation points (komi), handicap, and time control parameters. Rules that do not generally influence the game are: the tournament system, pairing strategies, and placement criteria.

In Unicode, Go stones can be represented with black and white circles from the block Geometric Shapes:

Go portrayed as part of East-Asian culture. (The goblet in the middle is from the Nihon Ki-in.)

A full set of Go stones (goishi) usually contains 181 black stones and 180 white ones; a 19×19 grid has 361 points, so there are enough stones to cover the board, and Black gets the extra odd stone because that player goes first. However it may happen, especially in beginners' games, that many back-and-forth captures empty the bowls before the end of the game: in that case an exchange of prisoners allows the game to continue.

It is considered poor manners to run one's fingers through one's bowl of unplayed stones, as the sound, however soothing to the player doing this, can be disturbing to one's opponent. Similarly, clacking a stone against another stone, the board, or the table or floor is also discouraged. However, it is permissible to emphasize select moves by striking the board more firmly than normal, thus producing a sharp clack. Additionally, hovering one's arm over the board (usually when deciding where to play) is also considered rude as it obstructs the opponent's view of the board.

Manners and etiquette are extensively discussed in 'The Classic of WeiQi in Thirteen Chapters', a Song dynasty manual to the game. Apart from the points above it also points to the need to remain calm and honorable, in maintaining posture, and knowing the key specialised terms, such as titles of common formations. Generally speaking, much attention is paid to the etiquette of playing, as much as to winning or actual game technique.

A 9×9 game with graphical aids. Colors and markings show evaluations by the computer assistant.

An abundance of software is available to support players of the game. This includes programs that can be used to view or edit game records and diagrams, programs that allow the user to search for patterns in the games of strong players, and programs that allow users to play against each other over the Internet.

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