Gomoku
The standard Gomoku board is a 14x14 square grid (this is the same as a 15x15 line grid). The game commences with the board vacant of counters.
Alternate Names
The full name of the game is Gomoku Narobe or Gomokunarabe, translating as “five stones in a row”. Other names for the game are Japanese Tic Tac Toe, Morphion, Itsutsu-ishi, or Pegety. The game was introduced into Britain as Gobang in the 19th century, probably a corruption of goban, which is the Japanese name for the Go board. In Korea, it is known as Omok (오목 [五目]). A game mentioned in a Japanese writing from CE 100 named Kakugo may be a Five-in-a-Row game. Pente and the Japanese game of Renju are more complex varieties of Gomoku. All of these games are sometimes called Five-in-a-Row games.
No. of Players
Two
Equipment
Gomoku is played on a 15x15 grid of intersecting lines that is identical to a Go board except for the size. This is the equivalent of a 14x14 square grid. When the smaller size board is not available a standard Go board is often utilized.
History
Gomoku originates from Japan.
Objective
The object of the game is to place five counters in a row on a board. The row can be horizontal, vertical, or diagonal. Often, a player wins by placing four counters in a line that is open on both ends, because the opponent can block only one end, and then the fifth counter is placed on the other end. The standard game requires a row of exactly five stones for a win: rows of six or more, called overlines, do not count.
Play
The counters are played on the intersections of the board. The game begins with Black placing the first counter at the center position of the board. White follows and the players take turns placing stones until one player achieves five stones in a vertical, horizontal, or diagonal row.
The player placing first has a tremendous advantage in this game to the point that experienced players following the above rules will always give victory to the player placing first. Because of this, more complex varieties of this game have been derived in order to take some of the advantage away from the first player.
A common and simple solution to first player advantage is the Swap2 rule, a slightly more elaborate pie rule. With the Swap2 rule, the first player places three stones (2 black and 1 white) on the board and then the second player has the option to play as Black or White or to then place 2 more stones (1 black and 1 white) and let the first player chose color.
Strategy
Variations
Free-style Gomoku allows a win to a player with an overline, that is, a row with five or more counters in a row.
Renju now has its own page.
Pente™, which is the number five in Greek, is a Gomoku variant created in 1978 by Gary Gabrel and marketed by Hasbro and Winning Moves. At the time of Pente’s invention, Gabrel was a dishwasher at Hideaway Pizza in Stillwater, Oklahoma. The game was implemented to be played by customers there on the checkerboard tablecloths while they waited for their order. Pente is still being played by college students and other visitors there as of 2009. Specifically, Pente is derived from a Gomoku variant called Ninuki-renju or Gomoku Ninuki, from which it is only a slight simplification. Pente is (usually) marketed and played on an 18x18 square grid, the same as a Go board. Note that marketed versions of the game often had four hemisphere designs on the edge of the board that covered some of the intersections of the board. These have been a source of confusion for many first-time players who wonder if they may place stones here. The official rules state that, yes, stones may be placed here at the twelve positions which the four hemispheres obscure. The first difference of Pente from Gomoku is that in Pente White has the opening move, rather than Black, placing at the center of the board. The notable difference, however, is that Pente allows for custodianship capturing of opposing stones. Capture occurs if a player places one stone on both sides of two opposing stones adjacent to each other, so that all four stones are now in a row (orthogonal or diagonal) with the two captured stones in the middle. Captured stones are then removed from the board. A capture may only take place on the capturing player’s turn, i.e. a player can safely place two stones between two opposing stones on their turn. A player may capture multiple pairs of opposing counters via custodianship in a single turn. In addition to the normal method of winning by forming five in a row, Pente can also be won by capturing ten (five pairs) of opposing stones.
In Pente, it is forbidden to play into a capture. As an example, if you are playing White and there is a row of stones on the board in the order Black-White-Vacant-Black you may not play at that vacant position.
Pente has some special terminology: as a a tessera is an unblocked row of four stones. For a player achieving a tessera, a win is imminent as the opponent will not be able to block both ends. A tria is an unblocked row of three stones that is a serious threat to the opponent. An unblocked row of three stones, if it contains one gap, is still considered a tria. It is customary, but not mandatory, refinement of of Pente to have a player announce "Tria" or "Tessera" when creating one of these formations. This could be seen as very similar to announcing "Check" and "Checkmate" from Chess.
Sometimes a tournament rule is implemented for play of Pente which is meant to take some of the advantage of the first player away. The tournament rule restricts white’s second move to be at least three intersections away from the center of the board.
Keryo-Pente is a variant of Pente, invented in 1983 by the then World Pente Champion, Rollie Tesh. Tesh claimed that under the current rules of Pente, White could always win with correct play, regardless of Black's plays and proposed rule changes for more balanced play. While normal Pente only allows for capture of pairs of opposing counters, Keryo-Pente allows for custodianship capture of groups of two or three opposing counters. To win with capture in Keryo-Pente a player must capture fifteen, rather than ten, opposing stones.
G-Pente is a variation of Pente proposed by Gary Barnes attempting to balance the game away from the first player advantage. This variation restricts the first player’s second move, just like the tournament rule. Additionally, it prohibits playing on the fourth and fifth intersections away from the center of the board that are one the same horizontal or vertical line as the first move. (These moves are the most common second moves for white).
D-Pente is a variation of Pente proposed by Don Banks again attempting to balance the game away from the first player advantage, this time using a sort of extended Pie Rule. Here, one player places the first four stones, two white and two black at any four positions on the board as long as one of the white stones is at the very center of the board. After those four stones have been places, the other player decides which color to play as. White will have the first move and play will continue as in normal Pente. This challenges the first player to lay the white stones at a unadvantaged position so that play is more balanced for Black.
Poof-Pente is a variation of Pente proposed by Tom Cooley. The main difference is that you can play into a capture. MORE INFO NEEDED
Boat-Pente is the same as normal Pente in all but that it allows an additional move after their opponent has made a Pente (Five-in-a-Row). If, in the additional move, the player captures stones from the Pente, the game may continue as before until one player makes an unstoppable Pente.
Boat-Pente is a variation of Pente proposed by player zoeyk. Also known as "boat rules" Pente.
The main difference between this game and Pente is in the end game. Once a Pente is made (5 stones in a row), the game can continue as long as the opponent is able to capture across the Pente! So in the example game below white hasn't won yet because black can capture on the next turn, removing the Pente. If after black moves the Pente is still in place then white wins. Capturing ten opposing stones 5 pairs is still a win as in normal Pente and the tournament rule is used.
Connect6 was introduced by Professor I-Chen Wu at the National Chiao Tung University. The rules are similar to gomoku, the object is to be the first player to get six or more stones in a row, orthogonally or diagonally. In Connect6, the first player places one black stone at the center of the board. After that, each player gets to place two stones on the board at a time. It is normally played on a Go board, but tournaments will often utilize a 58x58 square grid. This board has been improvised as nine Go boards placed together in a larger square and utilizing the join lines between the boards as additional grid lines.
Gomoku and Pente are both played with time limits placed on turns and the game itself. This can create a dramatically different game.
Sources
Schmittberger, R. Wayne. New Rules for Classic Games. John Wiley & Sons, Inc. New York, 1992. ISBN 0-471-53621-0
Provenzo, Asterie Baker and Eugene F. Provenzo, Jr. Play It Again, Historic Board Games You Can Make and Play. Prentice-Hall, Inc., 1981. ISBN 0-13-683367-5
Neto, Joāo Pedro and Jorge Nuno Silva. Mathematical Games, Abstract Games. Dover Publications, Inc. 2013. ISBN 978-0-486-49990-1
A page from Pente.org. https://pente.org/help/helpWindow.jsp?file=playGameRules