Black was long known to have a big advantage, even before L. Victor Allis proved that blackcould force a win (see below). So a number of variations are played with extra rules that aimed to reduce black's advantage.
* Free-style gomoku is the basic game as described above.
* Standardgomoku requires a row of exactly five stones for a win: rows of six or more, called overlines, do not count.
* The rule of three and three bans a move that simultaneously forms two open rows ofthree stones (rows not blocked by an opponent's stone at either end).
* Gomoku+(also called Caro, popular among Vietnamese) the winner must have an unbroken row of five stones and this row must notbe blocked at either end. This rule makes Gomoku more flexible and provides more power for White to defend.
* The rule of four and four bans a move that simultaneously forms two rows of four stones(open or not).
These restrictions are often applied only to black.
* Renju is played on a 15×15 board, with the rules of three and three, four and four, and overlines applied to black only.There are special rules for the opening.
* Ninuki-renju or Wu is a variant which adds capturing to the game; it was published in the USA in a slightly simplified form under the name Pente.
*m,n,k-games are a generalization of gomoku to a board with m×n intersections, and k in a row needed to win.
* Connect(m,n,k,p,q) games are another generalization of gomoku to a board with m×nintersections, k in a row needed to win, p stones for each player to place, and q stones for the first player to place for the first move only. Among these games, Connect(m,n,6,2,1) is the most interestingone, and is called Connect6.
Computer search by L. Victor Allis has shown that on a 15×15 board, black wins with perfect play. This applies regardless of whether overlines are...