In this game invented by American mathematician David Gale and described in Martin Gardner's column in "Scientific American" Oct. 1958, two grids of differently-colored dots are overlaid at an offset. One player links orthogonally adjacent dots on one grid, and the other player uses the other. One player attempts to link the top of their grid to the bottom, while the other tries to link their left side to the right. The game is equivalent to the Shannon switching game played on a rectangular grid. No draw can result; the first player can always win with correct play.