In 1975 Mark Berger, who's real name is Richard Kramberger, invented 'Rosette', a translation of Go to a hexagonal grid. Unlike some other hexagonal versions of Go, in this one pieces are placed on the vertices of the hexes, not the hexes themselves, so each stone has only three neighbors. The board he intended is a hexagonal grid in the shape of a hexagon, with seven hexagons on each side. This contains 294 vertices. MindSports also features base-6 and base-5 boards with 216 and 150 vertices, resp..

Play Rosette interactively

Shorthand
All rules of Go apply with one addition: a group containing a hexagon with all the vertices occupied by stones of one color (called a rosette) cannot be captured, even if it has no liberties.

Rosette positionRules
The board starts out empty. Both players, Black and White, have enough stones in their colour.

Placement
Players take turns, placing one of their stones on a vacant point at each turn. Black moves first. Moving is not compulsory: a player may pass his turn without losing the right to move on his next turn. The game ends if both players pass on successive turns.

Once played, stones are not moved, but they may be captured. Connected stones form a group that lives so long as at least one of its stones borders on one or more vacant points or if it contains a rosette. If a group without a rosette loses its last vacant point or 'liberty', it is captured and removed from the board.

Suicide
Placing a stone where it has no liberties is illegal. However, if a stone makes a capture it inherently gets a liberty by the removal of the captured stones. In such cases placement at a point with no liberties is legal.

Ko
A move may not result in a position that did occur before with the same player to move.

Object
Ultimately the object of the game is to conquer more territory than the opponent, so obviously after a game has ended, there's counting involved. There are two systems for counting: Japanese and Chinese. The difference may be one point.

Counting
  • The Japanese count the vacant points surrounded by a player plus the stones has captured. As a shortcut, these captured stones are placed inside the opponents territory, to reduce it with a corresponding number of points.
  • The Chinese count both a player's stones and the vacant points of territory surrounded by him. Captured stones do not matter since placing them inside the opponent's territory doesn't alter the score.

'Seki' may occur: vacant points that neither player can occupy without losing a group. Vacant points inside a seki do not count.

Komi
Black has an advantage the point value of which is not known and can only be guessed. We'd say that 4,5 or 5,5 is probably not too far off.


Rosette © Mark Berger