Tanbo

• Board
• Objective
• Play
• Removal of Stones
• External Links

Tanbo is played on a Go board (19x19). There are two players using black and white stones.

The initial position of the stones is shown in the following illustration:

During the game stones are added to and removed from the board.

The goal of Tanbo is to stay with at least one stone when all opponent's stones have been removed from the board.

No draws are possible in Tanbo.

Each player has an allocated color: Black or White.

Starting with Black, players take turns placing a stone of their color on any empty intersection of the board that is horizontally or vertically adjacent to exactly one like-colored stone. A player cannot place a stone on an intersection that is not adjacent to any of his stones or that is adjacent to two or more of his stones.

Below are some examples of possible moves for Black and White: 

A white stone can be placed where the transparent stones are shown because there is exactly one horizontally or vertically adjacent white stone.	A white stone cannot be placed where the transparent stones are shown because there is not exactly one horizontally or vertically adjacent white stone.	A black stone can be placed where the transparent stones are shown because there is exactly one horizontally or vertically adjacent black stone.

Tanbo is a game of "roots" - groups of connected stones of the same color. Players start the game with eight single-stone roots each. When placing a stone as described above, you are expanding one of your roots by connecting your stone to it. The basic move rule (your newly added stone must connect to exactly one of your other on-board stones) prevents the formation of clumps and closed loops in roots as well as the merger of like-colored roots.

The "current root" is the root a player connects a stone to on his turn.

A root is called "bounded" if it cannot be expanded, i.e. if no stone of the same color could be connected to it without violation of the rules.

If a player adds a stone and as a result the "current root" becomes "bounded" then all stones composing it (including the newely added stone) are removed from the board:

Black adds a black stone (shown with a white dot) to the black root at the bottom. The root becomes "bounded" and thus all stones composing it are removed from the board.

If the newely added stone doesn't cause the "current root" to become "bounded" but it bounds other roots (of either or both colors) then all stones composing those roots are removed from the board:

White adds a white stone (shown with a black dot) to the white root in the middle of the board. The current root is not "bounded" (there is one option for its expansion) and thus is not removed from the board. In contrast, the two roots at the top of the board (one black and one white) do become "bounded" and thus all stones composing them are removed from the board.

If the newly added stone causes both the "current root" and other roots to become "bounded", then only the "current root" is removed from the board.  After removing the "current root", the other roots which were temporarily "bounded" are no longer "bounded":

Black adds a black stone (shown with a white dot) to the top black root. The "current root" and two other roots (the top right white root and the bottom black root) all become "bounded". Only the "current root" is removed from the board. After removing the "current root", the other two roots which were temporarily "bounded" are no longer "bounded".

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