Apart from the board, Keil differs from Go in the idea of linked cells, which preserves crosscuts and ko by reducing the natural connectivity of the hex grid.
Play Keil interactively
Definitions
Two adjacent cells, and any stones on them, are linked if there is another cell adjacent to both that is the same type as at least one of them. Two cells are the same type if they are either both empty or both occupied by stones of the same color.
A group is a stone along with all other like-colored stones one could reach from it through a series of steps between linked stones of that color.
A liberty of a group is an empty cell linked to at least one stone in that group.
Similarly, a territory is an empty cell along with all other empty cells one could reach from it through a series of steps between linked empty cells. You own a territory if all stones linked to cells in that territory are of your color.
Play
Black plays first, then turns alternate. On your turn, you must pass or place a stone of your color on an empty cell. After a placement, remove all opponent's stones in groups without liberties. After all removals, the stone you placed must be part of a group with at least one liberty, and the current board position must be different from the board positions at the end of all your previous turns. Otherwise, your placement is illegal.
The game ends when both players pass in succession. The player with the higher score in the final position wins. A player's score is the number of stones of their color on the board, plus the number of cells in their territories, plus a komi in the case of White. The button is used to avoid ties.
Komi and button
The komi 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.
Note: in the MindSports Player Sections the komi and who plays first is set by the challenger. The challengee can accept or reject the challenge, but that's all. So coordination on komi and sides needs to be done beforehand, or refrained from altogether.
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.
An Example game
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to move
score
komi
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Luis Bolaños Mures - Kerry Handscomb
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External links
Keil © Luis Bolaños Mures