Spoint

Spoint is played on a 15x15 grid of squares. Two players take turns marking either an X (for player 1) or an O (for player 2) in an empty square. The first one to make an unbroken line of X's or O's in any direction (horizontally, vertically, or diagonally) of a predetermined length wins the game. Players may only place their marks in empty squares. If the board fills up before anyone has made a winning line, the game is a tie. Source: The Game Website.