overview
"Go-Moku" (Japanese - also spelled "Gomoku") or "wuziqi" (Chinese) is a very old game played with a Go set. The game can also be played on a sheet of graph paper using X's and O's. It is similar in idea to tic-tac-toe, but far greater in scale and complexity. The name means "five points."
It is debated whether this game originated in China or Japan, with more evidence pointing to the former.
The object is to get five stones in a row. The game is played on a 19x19 board (such as the board used in Go), creating a large and open field to complete this objective. The game can also be played on a smaller board, such as the popular 15x15 option.
If played perfectly, Black (who goes first) can always win the game. Even before this was proven, the game was recognized to be easier for Black. This problem is solved with the swap2 opening setup: place two black and a white stone; the other player then can take the white stones and play, take the black stones and pass, or place one more of each stone and give you the final choice. From then on play as normal, no need for during-play restrictions on black as in Renju which was often seen as the adult contemporary to the kids' Go-Moku.