You may not place a stone such that the stone or the group it is connected to has no more liberties. In the diagram, black may not play on the locations marked by X.

May white play there?

Yes, since by playing there, the black stones lose their last liberty and are removed, thereby giving white fresh liberties.

One may not play a move that recreates a previous situation. In the
diagram, white can capture the black stone, but black may not recapture
immediately. See also the strategy tips.

The game ends when both players pass. This usually happens when the players only have the choice between placing stones in their own territory or dead stones in the opponent's territory. Once both players pass, dead stones can be removed by clicking on them. Dead stones are those which can be captured no matter what the owner of the stone does (see also the strategy tips).
In the diagram, both white and black have one dead stone each.
Once all dead stones are removed, click on the "Beenden" button to confirm

Every live stone and every surrounded grid intersection counts as one point. In even (non-handicap) games, white is given 6 points ("komi") to even out the first play advantage of black.

In the diagram, black has 21 points in the upper left and in the lower right corners, 42 points total. White has 19 in the upper right and 20 in the lower left. Adding in the 6 point komi, white ends up with 45 points, therefore winning by 3.

While removing dead stones, accidental misclicks can be corrected using the undo button.

If there is a disagreement among the players about the status of a group of stones, play may be continued by clicking on the "Weiterspielen" button. In that case, the first player to pass moves first, and play may continue to resolve the conflict.

A player may resign by clicking on the "Aufgeben" button. Resignation requires that at least 20 moves have been played, and the winner is arbitrarily assigned a winning score of 20 points.

Several options are available, providing the full range of common go games:

/option 9|13|19

Sets the board size. The large 19x19 board is used by players familiar with the game. 9x9 is the recommended board size for beginners. A small board emphasizes tactical play, a larger board requires a more strategic outlook.

/option vorgabe 0..9

This sets the handicap. To even out differences in playing strength, the weaker player takes black and can set handicap stones onto predefined locations, giving him an advantage. In this case, white does not get the usual 6 point komi, but instead gets a komi equal to the number of handicap stones. A handicap of 1 denotes a normal game, but no komi for white.

Handicap is usually adjusted as the weaker player starts winning often, for example three games in a row.

/option time 1..60

This sets a timer. The player whose time expires automatically resigns. Time stops if a player drops connection. If the time left drops below "x" seconds, then the remaining time is set to "x" once that player moves. "x" is determined by the following table: