Introduction Whirlwind is a drawless connection game for two players: Black and White. It's played on the intersections (points) of an even-sized square board. The recommended sizes are between 12x12 and 20x20 points. The top and bottom edges of the board are colored black; the left and right edges are colored white. At the start of the game, some black and white stones are arranged on the board in an interspersed pattern such that every stone (except those on the edges of the board) is a knight's jump distance away from four enemy stones and a large knight's jump distance away from four friendly stones. Only symmetrical set-ups are allowed. For every board size, two different symmetrical set-ups exist (see the pictures). Play Black plays first, then turns alternate. On his turn, a player must place one one or two stones of his color on empty points of the board. On his first turn, Black can only place one stone. Passing is not allowed. At the end of a turn, any two like-colored, diagonally adjacent stones must share at least one orthogonally adjacent, like-colored neighbor. Objective The game is won by the player who completes a chain of orthogonally adjacent stones of his color touching the two opposite board edges of his color. Draws are not possible. Acknowledgements The ban on diagonal connections as a means to prevent deadlocks on square-board connection games was first used in Corey Clark's Slither.