The diagram shows a standard base-19 board. Play is on the intersections. There are two players, Black and White. Both have a sufficient number of bi-colored stones. At the start of the game the board is empty.

Sygo board
  • A 'group' is a single stone (by definition) or a number of orthogonally connected like colored stones.
  • White moves first. On his turn a player may either put a stone on a vacant point, not connected to a like colored group, thereby creating a new group, or grow any or all of his groups by one stone.
    Moving is not compulsory: a player may pass without losing the right to move next turn.
  • A stone connecting two or more different groups is considered to have grown all of them.
  • No group may grow more than one stone in a turn. However, if two groups are grown so that only the two newly grown stones touch, then the move is legal.

    Turn order balance
  • If, and only if, neither player has grown yet, then Black may grow any or all of his groups followed by a single stone placement, in the same turn.

The orthogonally adjacent vacant points of a group constitute its liberties.

  • Suicide is illegal: if at the completion of a move a stone or group of the moving player has no liberties itself, then the move is illegal.
  • If the placement of a single stone results in an opponent's group losing its last liberty, then this group is reversed immediately. This marks the end of the move. If this resulting group has no liberties either, then the move is suicidal and therewith illegal.
  • If the growth of a group results in an opponent's group losing its last liberty, then this group is reversed immediately to unite its captors in one group. The resulting group may not grow any further in the same turn.
  • In either case, the stone placed or the group grown to effectuate the capture, may at the moment of placement (growth) have no liberties itself, but if the resulting capture unites the captors in one group that is alive, then the move is legal.

examplesTop left black has grown at E19 and now may not grow at C18 because the original group D/E18 would had two new stones adjacent to it. For the same reason black cannot, in one turn, capture the white stones top right.

Middle left black may grow at the marked point. It is true that he thus does make contact with a group that already did grow, but only the two newly grown stones touch. For the same reason black can, in one turn, capture the white stones middle right.

Bottom left white may capture at A1 and the three black men are reversed immediately. That constitutes the beginning and the end of the turn. Black may thereafter capture the eight white stones by growing at the marked points.

Bottom right is a seki: neither can grow at Q1 without allowing the opponent the possibility of capturing the resulting group with a single placement.

examplesTop left white may not grow at D19: that would be suicide.
Top right, white can neither place at S19, nor grow at Q19: both would be suicide.

Bottom left white cannot capture by growing at B1, because the resulting white group would have no liberties, making the move suicidal.
Bottom right shows a ko isn't possible because a capture at Q3 would not open a ko but close P3.

The game ends by one player's resignation or when players pass on successive turns.
The winner is now the player with the largest terrirory, counted as stones plus surrounded vacant territory. In a seki only the vacant points that are completely surrounded by one player count.
Due to the possibility of a seki Sygo may on rare occasions end in a draw.

The dilemma
The dilemma is, to a substantial degree, how long to create new groups and when to start growing them. More groups are needed to be able to grow faster in the subsequent turns, but the more groups there are, the more tempting it becomes to be the first to grow, because of the initiative the combination of several growing moves allows. Tactical issues such as attacking moves by the opponent may also require growth in reply, so timing may vary.

Within the main dilemma, the move order balancing rule creates its own dilemma. Both players are faced with the choice of trading the move order advantage against the growth of a limited number of groups by the opponent, as is pointed out in About Symple.
Symple is the game that gave birth to the move protocol in which this turn order balancing mechanism is embedded.

Sygo © MindSports
Java applet © Ed van Zon