Go (game)

Lore & Background

Go was considered one of the four essential arts of the cultured aristocratic Chinese scholars in antiquity. The earliest written reference to the game is generally recognized as the historical annal Zuo Zhuan (c. 4th century BCE). The game reached Korea by the 2nd or 3rd century CE and Japan by the 5th or 6th century CE, by which time the 19×19 board had become standard.

The playing pieces are called stones, with one player using white and the other black. Players take turns placing stones on vacant intersections of the board. Once placed, stones may not be moved, but captured stones are immediately removed. A stone or connected group is captured when surrounded on all orthogonally adjacent points. The game proceeds until neither player wishes to make another move, and the winner is determined by counting surrounded territory, captured stones, and komi (points added to the score of White as compensation for playing second).

Despite its relatively simple rules, Go is extremely complex. Compared to chess, Go has a larger board with more scope for play, longer games, and many more alternatives to consider per move. The number of legal board positions in Go has been calculated to be approximately 2.1×10^170, far greater than the number of atoms in the observable universe.

Reader's Guide

Go is an adversarial game between two players with the objective of capturing territory by occupying and surrounding a larger total empty area of the board with one's stones than the opponent. Players place stones on the board, creating formations and enclosing spaces. Stones are linked together by being adjacent along the black lines, not on diagonals. Contests between opposing formations can result in expansion, reduction, or wholesale capture of formations and their enclosed empty spaces.

An essential aspect is that any formation of stones needs to have, or be capable of making, at least two enclosed open points known as eyes to preserve itself from capture. A formation with two or more eyes is unconditionally alive. The general strategy involves placing stones to fence off territory, attack the opponent's weak groups, and stay mindful of the life status of one's own groups. Situations where mutually opposing groups must capture each other are called capturing races, or semeai.

In the opening stages, players typically establish groups near the corners and sides of the board. Established corner opening sequences are called joseki. The game ends when both players pass or one resigns. Players' strength is indicated by rank (from 30 kyu to 1 kyu, then 1 dan to 7 dan, then 1 dan pro to 9 dan pro). A difference in rank may be compensated by a handicap. There are different rulesets (Korean, Japanese, Chinese, AGA, etc.), which are almost entirely equivalent except for certain special-case positions and scoring methods.

Did You Know?

• The name Go is a short form of the Japanese word igo, which derives from Middle Chinese ɦʉi gi (圍棋, Mandarin: wéiqí, meaning 'encirclement board game').
• A 2016 survey by the International Go Federation's 75 member nations found over 46 million people worldwide know how to play Go, with over 20 million current players, mostly in East Asia.
• The number of legal board positions in Go is approximately 2.1×10^170, far greater than the number of atoms in the observable universe (estimated at 10^80).
• Ko is a potentially indefinitely repeated stone-capture position; the rules do not allow a board position to be repeated.