Go is an abstract strategy board game for two players in which the aim is to surround more territory that the opponent. The game was invented in China more than 2,500 years ago and is believed to be the oldest board game continuously played to present day. The game is typically played on 3 size boards (9x9 - beginner, 13x13 - intermediate, 19x19 - expert).

Rules

The Official AGA rules of Go are used on this site.

The playing pieces are called stones, one player users the black stones and the other white. Black begins the game.

The players take turns placing a stone on the vacant intersections on the board. Once placed on the board, stones may not be moved, but stones can be removed from the board if the stone (or group of stones) is surrounded by opposing stones on all orthogonally adjacent points, in which case the stone or group is captured.

Players are not allowed to make moves that immediately return the game to a previous position (this rule is called the ko rule and prevents repetition). In the rare case of repetition (e.g. 3 ko's are repeated) a draw is automatically given.

In a given position, a liberty of a stone is an empty intersection adjacent to that stone or adjacent to a stone which is connected to that stone. A player may not place a stone such that it or its group immediately has no liberties unless doing so immediately deprives an enemy group of its final liberty (in this case it captures the enemy stones and therefore creates a liberty).

If a player does not want to place a stone, they may pass their turn (they may continue to play on a subsequent turn, if the opponent doesn't immediately also pass). To make a pass, a player should click the hand button which appears between the takeback and resign buttons.

Should both players consecutively pass their turn, then the game is paused. Dead stones are then agreed upon and removed from the board, the final score is calculated and the player with the highest score wins.

Dead Stone Offer

Once both players pass, the player's clocks are paused and the active player can select dead stones to offer to the opponent (they can offer 0). The opponent then has 3 options:

1. Select a different selection of stones and send back a new offer
2. Accept the offer - this ends the game
3. Decline the offer - this will reject the offer and return the players to the game and restart the clocks. The game essentially continues as though both players didn't pass. The active player may pass again or place a stone on the board. Once there are two consecutive passes the active player will have the option to select dead stones again.

During the dead stone offering phase, if the game was played using Fischer or Bronstein clocks then each player will have a separate timer (e.g. 60 seconds) to complete their choice. If a player runs out of time, they will either automatically accept the opponents offer, or offer 0 dead stones if no offer has been given yet.

Compensation

To allow players of different skills to compete fairly, handicaps and komi are used. These are considered a part of the game and, unlike in many other games, they do not distort the nature of the game. Players at all levels employ handicaps to make the game more balanced.

In an "even", or non-handicap game, Black's initial advantage of moving first can be offset by komi (compensation points): a fixed number of points, agreed before the game, added to White's score at the end of the game. Our standard Go game (for all sizes) uses a Komi of 7.5. A half point Komi ensures that the game cannot end as a tie.

Handicaps are given by allowing the weaker player to take Black and start the game with a number of stones on the board (in a preset configuration), white then continues the game from this setup position.

Whilst you can play a range of Komi's and Handicaps, to play a rated game on PlayStrategy (for all sizes) you must have Komi set to 7.5 and a Handicap of 0 stones.

Winning

There are two typical scoring methods used in Go, Chinese and Japanese scoring. While both are similar, on this site Chinese scoring is used. The Chinese scoring method counts all intersections surrounded by a player as one point (area), and adds this to the number of stones they have on the board. As white plays second, they add their Komi compensation to their score (usually worth an additional 7.5 points).

It is important to note that when using Chinese scoring, a player should fill neutral points before they pass. A player can proceed to capture dead stones, but this essentially has no effect on the end score.

During the game captured stones will be displayed in a blue box, this information will change to show the final score (in an orange box) during the dead stone offering phase and at game end.

For more information and explanation of the rules, including many detailed examples see Wikipedia.