Go is played on a square board printed with a grid of any size. The most common board sizes have either 9x9, 13x13 or 19x19 lines. The 19x19 grid is the official tournament size. The simplest way to explain the rules of the game it to look at a 7x7 board, however the rules are the same for all sizes of board. The game begins with an empty board*. The dark spot in the middle of the board is used both for orientation and as a marker for the placement of pieces in handicapped games (cf. section 7).

* With the exception of handicap games; see section 7 below.

A Go move involves placing a stone on one of the intersections on the board, as opposed to other games like chess and checkers, where pieces are placed in the spaces between the lines. In the figure above you will see the first four moves of an instruction game. The moves are numbered to indicate the order in which they were played.

That's right; in Go the black player moves first!

Another legal move, which is difficult to illustrate, is a pass, where one player chooses to miss a turn. Once both players have passed consecutively the game ends.

During a Go game one or more stones can be captured by completely surrounding them, i.e. filling all empty points around them. We show two examples: in the above figure a one stone capture, in the figure below a three stone capture.

After black has played his move at 1 in both figures he removes the captured white stones from the board as illustrated

Note : Needless to say, being captured is usually bad, however there are situations where one sacrifices one or more stones to gain advantage elsewhere.

The aim of Go is to conquer a larger part of the board than your opponent. The conquered part exists of the stones placed on the board plus the stones which could be added safely, i.e. inside your own walls. The figure shows a final position. The score for this game would be: black has 11 stones on the board and could add 16 stones inside his own walls, white has 11 stones on the board and could add 11 stones inside his own walls, so the score is 11+16 - 11+11 is 5 points for black. Black won this game.

You might argue that it is not fair that black won the game because he had the advantage of moving first. This is why the white player receives a compensation for the fact that he moves second, call-ed the komi (Japanese). Funnily enough, the komi hardly depends on the board size. According to Japanese professional Go players the komi should be 5.5 points for the board sizes 9x9, 13x13 and 19x19. In the above game we played on a 7x7 board. If we assume that the komi was 5.5 points, white would have won by 1/2 point, the smallest possible margin.

Note 1 : The komi value differs between diff-erent countries. It can even differ between different tournaments. Basically it is up to the organizer to decide with how much komi the game is played.

Note 2 : The komi includes half a point (5.5) to ensure that the game cannot end in a draw.

Imagine we have the following situation (i) with black to move and black decides to capture the white stone (ii).

In the resulting position (iii) white is to move and could now decide to capture a black stone (iv). The final position will be the same as the starting position (i).

This implies that this move sequence could repeat itself endlessly. To avoid this, the game has a special rule, the ko rule (Japanese) which prohibits the same position (i.e. the whole board!) repeating itself. In the diagram, (iv) would be prohibited by the ko rule.

One of the many nice features of Go is that you don't have to find an opponent of equal strength and experience to have an exciting game.

The Go game provides a handicap system which allows you even the game out by adding some initial stones on the board.

The larger the strength difference the more stones are added. These stones are called handicap stones and are placed on predefined points, indicated on the Go board by circles.

Here you see two examples: a handicap 3 and a handicap 9 game. The latter is usually considered the maximum for 19x19 Go and as you can see from the figure is far more than reasonable for 7x7.