Havannah (board game)

Havannah is a two-player abstract strategy board game invented by Christian Freeling. It is part of the connection games family, alongside Hex and TwixT. The game is known for having "a sophisticated and varied strategy" and is ideally played on a hexagonal board with ten cells per side. Ravensburger once published the game in Germany, offering a smaller eight-cell-per-side version for beginners. Today, Havannah is only produced by Hexboards.

In a standard game, one player uses black stones and the other white. Black makes the first move, and then turns alternate. On each turn, a player places one stone of their color on the board. Stones are never moved, captured, or otherwise altered. A player wins by completing one of three types of unbroken paths made from their own connected stones: a ring, which is a loop surrounding at least one cell (regardless of whether those cells are empty or occupied); a bridge, which connects any two of the board’s six corner cells; or a fork, which connects any three edges of the board (corner points do not count as part of an edge). Because the first player has a clear advantage, the pie rule is commonly used for fairness: after the first move, the second player may choose to switch sides. When players of different skill levels compete, the weaker player (playing white) may be allowed to place two or more stones on their first turn.

Unlike Hex, where a completely filled board always yields exactly one winning connection, a full Havannah board usually contains multiple winning structures—but the game ends as soon as the first one appears. Draws are technically possible in Havannah, but extremely rare; only one draw between human players has been recorded. Tactics are much easier to master than strategy, and skill differences between players can be large.

In 2002, Freeling offered a prize of 1000 euros (available through 2012) to any computer program that could beat him in a single game of a ten-game match. For many years, computer programs lagged far behind human players. Starting around 2010, some Havannah programs began using Monte Carlo tree search, which led to notable improvements. During the "Havannah Challenge 2012" (October 15–19, 2012), Freeling played ten games against three strong programs, playing at least one game as black and one as white against each. He lost the challenge when he had to resign a game as whit