*[Version 2. 2008-07-05. These are not the official
rules but a simplifying proposal by Robert Jasiek.]*

The game is for the two players *Black* and *White*, who
use black and white stones, respectively.

The *board* is a grid of, by
default, 19 horizontal and 19 vertical lines forming 361
*intersections*.

A *string *consists
of a stone and all same-coloured stones connected without
interruption via lines.

A *liberty*
of a string is an empty intersection adjacent via a line to at least
one of its stones.

A* capture*
is the removal of all opposing strings without liberty.

A *play*
places a player's stone on an empty intersection and then performs
any capture.

After a play, a *position
*is the current distribution of
black and white stones on the intersections.

A *move* is either a play or a pass.

The players alternate moves. Black starts on the empty board.

A play without capture may not create a player's string without liberty.

A play may not recreate a position just after any earlier play.

After the first succession of two passes, the players may

either agree on all the stones to be removed, remove them, and then determine the score

or disagree, continue to alternate moves to the second succession of two passes, and then determine the score.

The *score* is

the number of intersections occupied by black stones

plus the number of empty intersections surrounded only by black stones

minus the number of intersections occupied by white stones

minus the number of empty intersections surrounded only by white stones

minus the komi, which by default is 6.5,

minus 1 if White made the first pass.

The game is

Black's win if the score is greater than zero,

White's win if the score is smaller than zero,

a tie if the score is zero.