Vacu 2021

Vacu is a Go-like territory game for two players: Black and White. It is played on the intersections (points) of an initially empty square board. Each player must have access to a sufficient number of stones of their own color.

DefinitionsIn these rules, "adjacent" always means "orthogonally adjacent".

A group is a stone along with all other like-colored stones one could reach from it through a series of steps between adjacent stones of its color.

Similarly, a territory is an empty point along with all other empty points one could reach from it through a series of steps between adjacent empty cells. You own a territory if all stones adjacent to points in that territory are of your color.

A liberty of a group is an empty point adjacent to at least one stone in that group.

To flip a group is to replace all its stones with stones of the opposite color.

To suppress a group is to remove all its stones from the board.

Your score is the number of stones of your color on the board, plus the number of points in your territories, plus komi (see below) if you play White.

PlayBlack plays first, then turns alternate. On your turn, pass or place a stone of your color on an empty point. If this stone is part of a group with liberties, suppress all enemy groups without liberties. Otherwise, suppress your group without liberties and flip all enemy groups that had no liberties before the suppression. In the latter case, at least one group must be flipped for the move to be legal.

The game ends when either both players pass in succession or a player flips or suppresses the last enemy group on the board. The player with the higher score in the final position wins. The button is used to avoid ties.

If, after a board play, the same board position appears for the third time with the same player to move, the game ends in a draw. A pass is not a board play.

Komi and buttonKomi is the whole number of points which is added to White's score at the end of the game as a compensation for playing second. Before the game starts, the first player chooses the value of komi, and then the second player chooses sides. Alternatively, experienced players may agree on a standard value for all games.

The button is a special token which is placed next to the board at the start of the game. On your turn, if neither player has taken the button yet, you may not pass, but you may take the button instead of making a board play. At the end of the game, a half point is added to the score of the player who has taken the button. When checking for repetitions, two identical board positions are still considered different if the button had already been taken in one of them but not in the other.

VariantsConvacu: The top and bottom edges of the board are colored black; the left and right edges are colored white. If you have no other moves available, you must pass. Passing is otherwise not allowed. If, at the end of a turn, there is a group touching the two opposite board edges of its color, the owner of that group wins.