Go board game rules: how to play go

Aim of the game

You score a point for each empty point you surround with your stones. These points are your territory. You also score a point for each of your opponent's stones that you capture. At the end, White adds komi: a few points for moving second. The higher score wins.

The board and the first move

Stones go on the points where the lines cross, not inside the squares. You can also play on the edge and in the corners.

A full-size board has 19 by 19 lines. For your first games, use a 9x9 board. A game on it takes 10 to 20 minutes, and you soon see where your moves lead. After a few games, move up to 13x13, then to 19x19.

1. The board starts empty.
2. Draw lots to decide who plays Black. If one player is much stronger, the weaker player takes Black (see Handicap stones).
3. Black places the first stone on any empty point.
4. Then you take turns. On your turn, place one stone on an empty point or pass.

Once placed, a stone never moves. It stays where it is until it is captured.

Liberties and capture

A liberty is an empty point directly next to a stone along a line. A stone in the middle of the board has four liberties. On the edge it has three, and in a corner only two. Diagonal points are not liberties.

Stones of the same colour that touch along a line form a chain. The whole chain shares its liberties. Stones that touch only diagonally are not connected.

A stone or chain with only one liberty left is in atari. If the other player fills that last liberty, it is captured.

When your move fills the last liberty of an opponent's stone or chain, you capture it. Remove those stones straight away and keep them. They are your prisoners, worth one point each at the end. A single move can capture several chains.

Suicide is not allowed

You may not make a move that leaves your new stone, or the chain it joins, with no liberties. Such a move is called suicide.

There is one exception. If your stone fills the last liberty of an enemy chain, that chain is captured first. Its stones come off the board, so your stone now has liberties. That move is allowed.

Ko

Sometimes you capture a single stone, and your opponent could capture your capturing stone straight back. You could then retake it, and so on forever. This shape is called a ko.

The ko rule: after your stone is captured in a ko, you may not recapture on your very next move. Play somewhere else first. If the ko is still there on your next turn, you may recapture. Then your opponent has to wait in the same way.

Players usually use that move to make a threat elsewhere on the board, called a ko threat. If your opponent answers it, you can retake the ko. If they ignore it and resolve the ko, you carry out your threat instead.

The rule only forbids the immediate recapture of a single stone. Recapturing two or more stones is always allowed.

Very rarely, several kos on the board make the same position repeat again and again. If neither player gives way, the Japanese rules declare no result, and you play a new game.

Living and dead groups

An eye is an empty point, or a small empty area, enclosed by one player's stones. An opponent's stone played into a one-point eye has no liberties of its own. Such a move is allowed only when it captures.

A group with two separate eyes can never be captured. A stone played into one eye would have no liberties while the other eye is still empty. That would be suicide, so it is not allowed. Such a group is alive.

A group that can neither make two eyes nor escape will be captured sooner or later. At the end of the game such stones are dead, even if they are still on the board.

Sometimes a black group and a white group share their last liberties, and neither has two eyes. Whoever plays on a shared liberty first puts their own group in atari and loses it. So neither player plays there, and both groups live. This is called seki.

Passing and the end of the game

Instead of placing a stone, you may pass. Passing is always allowed. Pass when no move would gain you anything: your borders are closed and none of your stones are in danger.

When both players pass in a row, play stops. If one player passes and the other places a stone, the game simply goes on.

1. Point out the stones you think are dead: stones that cannot avoid capture.
2. If you agree, take the dead stones off the board. They become prisoners of the player who surrounded them.
3. If you disagree, play on. Whoever asks to play on lets the other player move first. Continue until the stones in question are captured or clearly safe, then pass again.
4. Count the score (see Scoring).

You may also resign at any time. Your opponent then wins.

Scoring

Your territory is all the empty points surrounded only by your living stones and the edge of the board. Each point of territory is worth one point. Each prisoner is worth one point too, including the dead stones you removed at the end.

Some empty points touch living stones of both colours. These neutral points are worth nothing to either player. Players usually fill them in before passing, so the borders are clear. The empty points inside a seki are worth nothing either.

Add up your territory and your prisoners. White also adds komi. The player with more points wins.

In this example White wins by 2.5 points.

Komi

Moving first is an advantage. To make up for it, White gets extra points at the end, called komi. In an even game with territory scoring, komi is 6.5 points on every board size.

The half point means the game cannot end in a draw. With area scoring, as in the Chinese rules, komi is 7.5 points (see Area scoring). In a handicap game komi is usually just half a point.

Handicap stones

When one player is much stronger, the weaker one gets a head start. The weaker player takes Black and places 2 to 9 stones on the board before play starts. These are the handicap stones. Then White makes the first move.

On a 19x19 board the handicap stones go on the star points, the nine dots marked on the board. Seen from Black's side, they go here:

On a 9x9 board the five dots mark the handicap points. Use the same order: top right, bottom left, bottom right, top left, then the centre.

Each stone makes up for about one rank of difference in strength. If the gap is only one rank, the weaker player simply takes Black and White gets no komi. On 13x13 and 9x9 boards each stone counts for much more, so give far fewer stones. A gap worth nine stones on 19x19 is about four stones on 13x13 and about two on 9x9.