Copyright (c) 1995 Mark Steere tanbo@ix.netcom.com

Initially, each player has 8 stones on the board as shown in the next image. The stones are interspersed and evenly spaced over the entire board.

After setting up this initial configuration, black makes the first move. (A "move" will always mean adding exactly one stone to the board. Stones are never actually moved from one point to another on the board.) Next white makes a move, and the players continue to take turns adding their stones to the board until one player wins. A newly added stone must "connect" to exactly one stone of the same color, which is already on the board. Two points "connect" if they are horizontally or vertically adjacent. Diagonally adjacent points do not connect. Players are not allowed to pass. You must add exactly one stone to the board during your turn.

When a single root becomes so constricted that it can no longer grow, the entire root is immediately removed from the board. The surrounding roots can then grow into the area vacated by the removed root. (That is what would happen to the example roots concerning cells [2], [3] and [5]). Sometimes two or more roots will run out of growing space simultaneously (the roots around cell [2]).A root becomes "bounded" when a move is made which completely deprives that root of root space. When a player makes a move which causes one or more roots to become bounded, he will be required to remove at least one of these bounded roots from the board, during his current turn. There are more rules, that consider all other possible cases, you can read them here (there is also a FAQ available). To win, a player must eliminate all eight of his opponent's roots. One player will always win. It's impossible to repeat a board configuration in Tanbo. Therefore a game cannot result in a draw. 

An example

Cell [1] is legal to both White and Black since they would connect to an opponent piece (and so, the piece would not connect 2 stones of the same color). White cannot play at [2]. Cell [3] is legal to both players. Cell [4] is a legal move for Black. Cell [5] is a legal move for White..

Two variations are Hexbo and Tanbo 3D.