Gomoku！

Gomoku, Gobang or Five in a Row is a simple board game, it is usually played with Go pieces on a Go board with 19x19 intersections. The rule of this game is very simple (well, actually the current official Gomoku rule is not simple), two players place piece on an empty intersection in turn, the winner is the first player who gets five pieces in a row (next to each other) horizontally, vertically or diagonally.