Curious if anyone here has played this fascinating Japanese board game, which uses the same equipment as Go (though a smaller board). I had never heard of it, but ran across it recently while reading "The Master of Go" by Yasunari Kawabata, which features a character named Takagi, who is a Master of Renju.
It is the professional variant of Gomoku, with numerous restrictions on black's moves in order to equalize white's chances. The goal is to connect five stones in a row, horizontally, vertically, or diagonally, but much of white's strategy involves forcing black to violate one of its restrictions. It has fascinating openings, traps, and "threats."
Like draughts, the rules are simple, but the game is "replete with hidden wonders," as Robert McCulloch might say.