Game board


Game set consists of wooden board and two bowls with stones. Board is marked with the matrix of 19x19 lines, giving 361 intersections. In theory there are 180 white stones in a bowl and 181 black stones. This has no impact on the game. It is sufficient to state that there are enough stones. Nine intersections, marked for better orientation, are known as star points.

Moves and liberties

       
Stones are placed alternatively on empty intersections. Once put, stone can't be moved, except when removed as a prisoner, if it's chain loses last liberty.
Every empty intersection, adjacent to the stone and connected by drawn line with it, counts as one liberty [ white dot].
Stone in the corner has two liberties, on the side three and in center four liberties.

Black on move
Before  Black    Taking   After
move    plays   white's   move
           
Legal moves: stone can be placed on any empty intersection, under condition that after finished move this stone or it's chain retains at least one liberty on the board. Move consists of two phases: placing the stone and removing all stones of opposite color which lost their last liberty by this move, thereby losing the right to survive on board.

White on move
can't play on this intersections
   
Forbidden moves: In the case there was no removal of enemy stones, and newly put stone would not have a single liberty, player is not allowed to play on this intersection. This intersection is also called an eye. If the eye is false it is only temporary protected, until the opponent fills other surrounding liberties. Group with two real eyes, or which can't be reduced to only one eye is called live group. Live group stays on the board until the end of the game.

Continuous repetition
is not allowed

Forbidden repetition: Additional restriction is making the same position consequtively with the same player on the move. This rule is known as ko fight (in japanese 'ko' means 'eternity'). If it is important, player would play elsewhere on the board (ko threat), forcing his opponent to answer or suffer some damage. If he answers, ko fight continues. This technique gives much life to the game, offering possibilities for nice combinations.

Seki

Joined life or seki: by playing it is possible to reach positions where neither group has independent life, but all the same can't be taken. Who forces and plays first, he loses. This groups are left on board till the end of the game, but do not count in score. In given example marked intersection is before last liberty for both sides. Once one player fills it, other player on move fills last liberty of enemy stones so removing them from board as prisoners.

Game example



Diagram 1.
Position after 50 moves.
Aim of the game is to take (surround) as much space as possible. Game starts with empty board and playing continues so long as it gives profit. Every empty intersection under control of one player counts as one point, and every opponent's stone removed from the board or captured (dead) on the board is worth the same. In one moment a player on the move has either to fill an intersection of territory under his control, or give a prisoner playing in opponent's territory. In either case he stands to lose one point, so he 'passes'. If his opponent agrees there is nothing more to gain, he passes too and scoring begins. Player with the positive score wins. Intersections in seki positions do not count, and also common intersections between live opponent groups. Later are called 'useless' or 'dame' in japanese.


Go is a noncompromising game. To eliminate ties, which are rare by themselves, it is usual to rule that in a case of equal score, white wins. Black always play first, as in east black color is more noble than white. In equal games white gets some points for playing second. In handicap games black places one to nine stones as his first move, customary on star points.

Degrees of strength. Players are categorized as masters (dan) and apprentices (kyu). Degrees of professional players are closer in strength than amateur ones. So strongest professional is 9.dan and weakest master is 1.dan. Professional 1.dan is by the way stronger than amateur 5.dan. Amateur degrees go from 7.dan (somewhat equal to 5.dan professional) to 1.dan. Weaker degrees are 1.kyu (something as a 'master candidate') all the way downto 25.kyu, as the weakest player just learning the rules. Practical difference between two amateur can be put as 10 points, so the equal game komi that black gives to white for playing first is about five to six points.

You can try on-line playing at Pandanet Internet Go Server.