Anda

Introduction:Anda (from Proto-Germanic: Anþą, which means "breath") is a drawless game for two players: Black and White. It is played at the intersections (points) of an initially empty hexagonal board with triangles. The recommended size is 9 points per side, but it can be played on a 11–sized board for longer games or a 7–sized board for shorter games. There is also an off-board location called the prison. Each player has access to a sufficient supply of stones of their own color.



Definitions:– A group is a set of connected stones of the same color among themselves. A single stone is also a group.
– A liberty is an empty point adjacent orthogonally or diagonally to a group.
– A smothered group is a group where all its liberties has a path of N empty points connected to exactly one enemy supergroup, where N can be zero.
– A territory is a set of connected empty points. You own a territory if all the stones connected to it are your color.
– To annihilate is to place a stone on an empty point that smother all enemy groups, leaving the board with stones only of your color. You cannot annihilate if your opponent also annihilated in a previous turn.



Turns:Black plays first, then turns alternate. On your turn, do one of the following actions:

– Place a stone of your color on an empty point where it is not smothered, then move all smothered friendly and enemy groups to the prison. If it's your first turn, do it twice on non-adjacent empty points.
– Remove an enemy stone from the prison.

At the end of your turn, the group of the stone you placed cannot be smothered.



End of the game:– The player who performed the last action wins the game, so passing the turn is not allowed.
– One player has the option to “propose ending” to the game and the other player must accept it or not. If accepted, the points will be counted by adding the friendly territory and the enemy prisoners, in addition to granting an extra half point to the player who made the last move.

For the game to be fair, before it starts:

– Player 1 places two black stones.
– Player 2 either (i) swaps or (ii) places two white stones.
　– If (i), Player 1 places two white stones and Player 2 either swaps or accepts.
　– If (ii), Player 1 either swaps or accepts.

Then, the player with the black stones offers a komi pie, where the first player places several black stones in the prison and the second player chooses a side. The player with the white stones either swaps or accepts. I have called this balancing method dual pie rule.



Variant:For a simpler option, each player places two stones of their color on non-adjacent corners during game setup. Then Black starts the game by playing the first normal turn. The komi pie can also be used for balance.



Notes:Special thanks to Christopher Field for his contribution to a simpler alternative balancing method. The prison mechanism was introduced by David Wolfe and Elwyn Berlekamp in their book "Mathematical Go: Chilling Gets the Last Point".

—description from the designer