The general idea
The goal "Largest Group, Cascading" works like this. In a final position both contestants have groups and the largest ones of both are compared. If unequal, the largest one wins the game. If equal, then the next largest ones of both are compared. These may be the same size or smaller, but either way, if they are of the same size then the next largest ones are compared. That's the 'cascading' part and it goes on till a decision has been reached. Crossbars' goal is "Longest Bar, Cascading" and it works exactly the same way, except that 'bars' are compared. On boards with an even number of cells this may - in very rare cases - lead to a draw. Otherwise the game is decisive.

A square board and enough black and white stones.

A 'bar' is a maximal orthogonal straight line of same coloured stones. Part of a bar is not a bar.


  • Players, Black and White, alternate in compulsory placing one stone of their colour on an empty intersection. White places first and Black is entitled to a swap.
  • If a placement results in one opponent's stone being trapped diagonally between two stones of the moving player - one being the one that is placed and the other one already present on the board - then this stone is replaced by one of the moving player.
  • If the placed stone also traps another opponent's stone in the same way in the opposite or in a perpendicular direction, then this stone is also replaced by one of the moving player. Theoretically a maximum of four opponent's stones may be captured thus with one placement, however unlikely it is to actually happen.

Barring resignation, the game ends when the board is full. Winner is the player with the Longest Bar, Cascading. For White only horizontal bars count, for Black only vertical ones.

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