Y (game)

Y is an abstract strategy board game, first described by John Milnor in the early 1950s. The game was independently invented in 1953 by Craige Schensted and Charles Titus. It is a member of the connection game family inhabited by Hex, Havannah, TwixT, and others; it is also an early member in a long line of games Ea has developed, each game more complex but also more generalized.

Y is typically played on a triangular board with hexagonal spaces; the "official" Y board has three points with five-connectivity instead of six-connectivity, but it is just as playable on a regular triangle. Schensted and Titus' book Mudcrack Y & Poly-Y has a large number of boards for play of Y, all hand-drawn; most of them seem irregular but turn out to be topologically identical to a regular Y board.

As in most games of this type, one player takes the part of Black and one takes the part of White; they place stones on the board one at a time, neither removing nor moving any previously placed stones. The pie rule can be used to mitigate any first-move advantage.

The rules are as follows:

As in most connection games, the size of the board changes the nature of the game; small boards tend towards pure play, whereas larger boards tend to make the game more strategic.

Schensted and Titus argue that Y is a superior game to Hex because Hex can be seen as a subset of Y. Consider a board subdivided by a line of white and black pieces into three sections. The portion of the board at the bottom-right can then be considered a 5×5 Hex board, and played identically. However, this sort of artificial construction on a Y board is extremely uncommon, and the games have different enough tactics (outside of constructed situations) to be considered separate, though related.

Mudcrack Y & Poly-Y also describes Poly-Y, the next game in the series of Y-related games; after that come Star and *Star.

Y, like Hex, yields a strong first-player advantage. The standard approach to solving this difficulty is the "pie" rule: one player chooses where the first move will go and the other player then chooses who will be the first player.

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