Hexsygo is the hexagonal version of Sygo. It is played on a hexagonal board with a honeycomb grid. The diagram shows a standard base-10 board. Go and the hex grid are usually at odds with one another and the central problem in a Go variant with 'flip capture' is getting 'life'. But Sygo seamlessly adapts to the hex grid because the Symple move protocol inherently allows ways to secure life.

Rules
Hexsygo boardThere 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.

  • A group consists of one stone or two or more like colored connected stones. A single stone is a group by definition.
  • White moves first. On his turn a player may either put a stone on a vacant cell, 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.


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

  • If a placement or growing move does not result in a capture, it may never result in the stone or group of the moving player having no liberties itself. In other words: suicide 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 to unite its captors in one group. 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. Such a group may not grow any further in the same turn. If the resulting group has no liberties itself, then the move is suicidal and therewith illegal.
  • 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 the resulting capture unites the captors in one group that, if alive, unites the captors in liberty.

examplesExamples
Top: black can capture the three white stones, but if he does, the resulting group can be captured by white.

Topleft: black has grown (white circle) and now can no longer grow the other group at the cell marked 'x' because the first group would then have grown at two cells.

Top right: for the same reason black cannot capture the white group in one turn.

Bottom left: black has grown (white circle) but now connecting at K3 is legal because only the grown stones touch.

Bottom right: for the same reason black can capture the white group in one turn.

Bottom: this is a seki - black cannot capture because the remaining group would only have one eye, and white cannot capture because it would require suicide. The cell completely surrounded by black counts as his territory, the other vacant cell is neutral.


Object
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.
On rare occasions Hexsygo may 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. Apart from that, 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.

How I invented ... Sygo
Using the Hexsygo applet


HexSygo © MindSports
Java applet © Ed van Zon