Tic-tac-toe
Encyclopedia
Tic-tac-toe, also called wick wack woe (in some Asian countries) and noughts and crosses (in the UK, Australia, New Zealand, South Africa, India and the rest of the British Commonwealth countries), is a pencil-and-paper game
for two players, X and O, who take turns marking the spaces in a 3×3 grid. The X player usually goes first. The player who succeeds in placing three respective marks in a horizontal, vertical, or diagonal row wins the game.
The following example game is won by the first player, X:
Players soon discover that best play from both parties leads to a draw. Hence, tic-tac-toe is most often played by young children.
The friendliness of tic-tac-toe games makes them ideal as a pedagogical tool for teaching the concepts of good sportsmanship and the branch of artificial intelligence
that deals with the searching of game tree
s. It is straightforward to write a computer program
to play tic-tac-toe perfectly, to enumerate the 765 essentially different positions (the state space complexity), or the 26,830 possible games up to rotations and reflections (the game tree complexity) on this space.
However, according to Claudia Zaslavsky's book Tic Tac Toe: And Other Three-In-A Row Games from Ancient Egypt
to the Modern Computer, Tic-Tac-Toe could originate back to ancient Egypt.
The different names of the game are more recent. The first print reference to "noughts and crosses", the British name, appeared in 1864. The first print reference to a game called "tick-tack-toe" occurred in 1884, but referred to "a children's game played on a slate, consisting in trying with the eyes shut to bring the pencil down on one of the numbers of a set, the number hit being scored". "Tic-tac-toe" may also derive from "tick-tack", the name of an old version of backgammon
first described in 1558. The U.S. renaming of noughts and crosses as tic-tac-toe occurred in the 20th century.
In 1952, Tic-tac-toe became the first known video game, OXO
(or Noughts and Crosses) for the EDSAC
computer. The computer player could play perfect games of tic-tac-toe against a human opponent.
In 1975, Tic-Tac-Toe was also used by MIT
students to demonstrate the computational power of Tinkertoy
elements. The Tinkertoy computer, made out of (almost) only Tinkertoys, is able to play Tic-Tac-Toe perfectly. It is currently on display at the Museum of Science, Boston
.
Despite its apparent simplicity, Tic-tac-toe requires detailed analysis to determine even some elementary combinatory facts, the most interesting of which are the number of possible games and the number of possible positions. A position is merely a state of the board, while a game usually refers to the way a terminal position is obtained.
A naive count of the number of positions leads to 19,683 possible board layouts (39 since each of the nine spaces can be X, O or blank), and a similar count of the number of games leads to 362,880 (i.e. 9!
) different sequences for placing the Xs and Os on the board. However, this doesn't take into account the fact that the game ends when three-in-a-row is obtained. Many of the 19,683 positions are unreachable in an actual game.
The complete analysis is further complicated by the definitions used when setting the conditions, like board symmetries.
If board symmetries are taken into account, two games are considered the same if the sequence of board modulo the symmetries is the same. With the use of computer, Steve Schaeffer determined in 2002 that the number of games in these conditions is 26,830.
The first player, whom we shall designate "X", has 3 possible positions to mark during the first turn. Superficially, it might seem that there are 9 possible positions, corresponding to the 9 squares in the grid. However, by rotating the board, we will find that in the first turn, every corner mark is strategically equivalent to every other corner mark. The same is true of every edge mark. For strategy purposes, there are therefore only three possible first marks: corner, edge, or center. Player X can win or force a draw from any of these starting marks; however, playing the corner gives the opponent the smallest choice of squares which must be played to avoid losing.
The second player, whom we shall designate "O", must respond to X's opening mark in such a way as to avoid the forced win. Player O must always respond to a corner opening with a center mark, and to a center opening with a corner mark. An edge opening must be answered either with a center mark, a corner mark next to the X, or an edge mark opposite the X. Any other responses will allow X to force the win. Once the opening is completed, O's task is to follow the above list of priorities in order to force the draw, or else to gain a win if X makes a weak play.
, pente
, gomoku
, Qubic
, Connect Four
, Quarto
, Gobblet
. Generalizing the original Tic-tac-toe game, we get the
-game, played on the 
-dimensional cube with edge 
. Then, the ordinary Tic-tac-toe is the 
-game. The m,n,k-games are a family of generalized game
s based on tic-tac-toe.
In the United States, the name "noughts and crosses" is not well understood, as the word "nought" is archaic in usage and X-shaped objects are not generally called crosses except in the case of specific named crosses like St. Patrick's Cross.
Sometimes, the games Tic-tac-toe (where players keep adding "pieces") and Three Men's Morris (where pieces start to move after a certain number have been placed) are confused with each other.
, tic-tac-toe is used as an allegory for nuclear war
. In the climax of the film, the protagonist prevents an out of control military defense computer from launching nuclear missiles by making it repeatedly play tic-tac-toe against itself. After quickly learning that good strategy by both players produces no winner, the computer then plays through all known nuclear strike scenarios, again finding no winner. The computer concludes, "Strange game. The only winning move is not to play."
Various game show
s have been based on Tic-Tac-Toe and its variants:
Paper and pencil game
Paper-and-pencil games are games that can be played solely with paper and pencil .In some board games, including some abstract strategy games like Gomoku, a piece once played will not be moved on the board or removed from the board...
for two players, X and O, who take turns marking the spaces in a 3×3 grid. The X player usually goes first. The player who succeeds in placing three respective marks in a horizontal, vertical, or diagonal row wins the game.
The following example game is won by the first player, X:
The friendliness of tic-tac-toe games makes them ideal as a pedagogical tool for teaching the concepts of good sportsmanship and the branch of artificial intelligence
Artificial intelligence
Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...
that deals with the searching of game tree
Game tree
In game theory, a game tree is a directed graph whose nodes are positions in a game and whose edges are moves. The complete game tree for a game is the game tree starting at the initial position and containing all possible moves from each position; the complete tree is the same tree as that...
s. It is straightforward to write a computer program
Computer program
A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...
to play tic-tac-toe perfectly, to enumerate the 765 essentially different positions (the state space complexity), or the 26,830 possible games up to rotations and reflections (the game tree complexity) on this space.
History
An early variant of Tic-tac-toe was played in Roman Empire, around the first century BC. It was called Terni Lapilli and instead of having any number of pieces, each player only had three, thus they had to move them around to empty spaces to keep playing. The game's grid markings have been found chalked all over Rome.However, according to Claudia Zaslavsky's book Tic Tac Toe: And Other Three-In-A Row Games from Ancient Egypt
Ancient Egypt
Ancient Egypt was an ancient civilization of Northeastern Africa, concentrated along the lower reaches of the Nile River in what is now the modern country of Egypt. Egyptian civilization coalesced around 3150 BC with the political unification of Upper and Lower Egypt under the first pharaoh...
to the Modern Computer, Tic-Tac-Toe could originate back to ancient Egypt.
The different names of the game are more recent. The first print reference to "noughts and crosses", the British name, appeared in 1864. The first print reference to a game called "tick-tack-toe" occurred in 1884, but referred to "a children's game played on a slate, consisting in trying with the eyes shut to bring the pencil down on one of the numbers of a set, the number hit being scored". "Tic-tac-toe" may also derive from "tick-tack", the name of an old version of backgammon
Backgammon
Backgammon is one of the oldest board games for two players. The playing pieces are moved according to the roll of dice, and players win by removing all of their pieces from the board. There are many variants of backgammon, most of which share common traits...
first described in 1558. The U.S. renaming of noughts and crosses as tic-tac-toe occurred in the 20th century.
In 1952, Tic-tac-toe became the first known video game, OXO
OXO
OXO was a computer game written for the EDSAC computer in 1952, an implementation of the game known as Noughts and Crosses in the UK, or tic-tac-toe in the United States. It was written by Alexander S. Douglas as an illustration for his Ph.D. thesis on human-computer interaction for the University...
(or Noughts and Crosses) for the EDSAC
EDSAC
Electronic Delay Storage Automatic Calculator was an early British computer. The machine, having been inspired by John von Neumann's seminal First Draft of a Report on the EDVAC, was constructed by Maurice Wilkes and his team at the University of Cambridge Mathematical Laboratory in England...
computer. The computer player could play perfect games of tic-tac-toe against a human opponent.
In 1975, Tic-Tac-Toe was also used by MIT
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
students to demonstrate the computational power of Tinkertoy
Tinkertoy
The Tinkertoy Construction Set was created in 1914—one year after the A. C. Gilbert Company's Erector Set—by Charles H. Pajeau and Robert Pettit in Evanston, Illinois. Pajeau, a stonemason, designed the toy after seeing children play with pencils and empty spools of thread. He and...
elements. The Tinkertoy computer, made out of (almost) only Tinkertoys, is able to play Tic-Tac-Toe perfectly. It is currently on display at the Museum of Science, Boston
Museum of Science, Boston
The Museum of Science is a Boston, Massachusetts landmark, located in Science Park, a plot of land spanning the Charles River. Along with over 500 interactive exhibits, the Museum features a number of live presentations throughout the building every day, along with shows at the Charles Hayden...
.
Combinatorics
A naive count of the number of positions leads to 19,683 possible board layouts (39 since each of the nine spaces can be X, O or blank), and a similar count of the number of games leads to 362,880 (i.e. 9!
Factorial
In mathematics, the factorial of a non-negative integer n, denoted by n!, is the product of all positive integers less than or equal to n...
) different sequences for placing the Xs and Os on the board. However, this doesn't take into account the fact that the game ends when three-in-a-row is obtained. Many of the 19,683 positions are unreachable in an actual game.
The complete analysis is further complicated by the definitions used when setting the conditions, like board symmetries.
Number of terminal positions
When considering only the state of the board, and after taking into account board symmetries (i.e. rotations and reflections), there are only 138 terminal board positions. Assuming that X makes the first move every time:- 91 unique positions are won by (X)
- 44 unique positions are won by (O)
- 3 unique positions are drawn
Number of possible games
Without taking symmetries into account, the number of possible games can be determined by hand with an exact formula that leads to 255,168 possible games (see Henry Bottomley, 2001, or Steve Schaeffer, 2002). Assuming that X makes the first move every time:- 131,184 finished games are won by (X)
- 77,904 finished games are won by (O)
- 46,080 finished games are drawn
If board symmetries are taken into account, two games are considered the same if the sequence of board modulo the symmetries is the same. With the use of computer, Steve Schaeffer determined in 2002 that the number of games in these conditions is 26,830.
Strategy
A player can play perfect tic-tac-toe (win or draw) given they move according to the highest possible move from the following table.- Win: If the player has two in a row, play the third to get three in a row.
- Block: If the [opponent] has two in a row, play the third to block them.
- Fork: Create an opportunity where you can win in two ways.
- Block opponent's Fork:
- Option 1: Create two in a row to force the opponent into defending, as long as it doesn't result in them creating a fork or winning. For example, if "X" has a corner, "O" has the center, and "X" has the opposite corner as well, "O" must not play a corner in order to win. (Playing a corner in this scenario creates a fork for "X" to win.)
- Option 2: If there is a configuration where the opponent can fork, block that fork.
- Center: Play the center.
- Opposite corner: If the opponent is in the corner, play the opposite corner.
- Empty corner: Play in a corner square.
- Empty side: Play in a middle square on any of the 4 sides.
The first player, whom we shall designate "X", has 3 possible positions to mark during the first turn. Superficially, it might seem that there are 9 possible positions, corresponding to the 9 squares in the grid. However, by rotating the board, we will find that in the first turn, every corner mark is strategically equivalent to every other corner mark. The same is true of every edge mark. For strategy purposes, there are therefore only three possible first marks: corner, edge, or center. Player X can win or force a draw from any of these starting marks; however, playing the corner gives the opponent the smallest choice of squares which must be played to avoid losing.
The second player, whom we shall designate "O", must respond to X's opening mark in such a way as to avoid the forced win. Player O must always respond to a corner opening with a center mark, and to a center opening with a corner mark. An edge opening must be answered either with a center mark, a corner mark next to the X, or an edge mark opposite the X. Any other responses will allow X to force the win. Once the opening is completed, O's task is to follow the above list of priorities in order to force the draw, or else to gain a win if X makes a weak play.
Variations
Many board games share the element of trying to be the first to get n-in-a-row: three men's morris, nine men's morrisNine Men's Morris
Nine Men's Morris is an abstract strategy board game for two players that emerged from the Roman Empire. The game is also known as Nine Man Morris, Mill, Mills, Merels, Merelles, and Merrills in English....
, pente
Pente
Pente is a strategy board game created in 1977 by Gary Gabrel, based on the Japanese game ninuki-renju, a variant of renju or gomoku which is played on a Go board of 19 x 19 intersections with white and black stones. In contrast to renju, ninuki-renju and Pente allow captures, but Pente added a...
, gomoku
Gomoku
Gomoku is an abstract strategy board game. Also called Gobang or Five in a Row, it is traditionally played with go pieces on a go board ; however, because once placed, pieces are not moved or removed from the board, gomoku may also be played as a paper and pencil game...
, Qubic
Qubic
Qubic is the brand name of a four-in-a-row game played in a 4×4×4 matrix sold by Parker Brothers starting in 1953. The original box, and the 1972 reissue, described the game as "Parker Brothers 3D Tic Tac Toe Game." Players take turn placing pieces to get four in a row horizontally or...
, Connect Four
Connect Four
Connect Four is a two-player game in which the players first choose a color and then take turns dropping their colored discs from the top into a seven-column, six-row vertically-suspended grid...
, Quarto
Quarto (board game)
Quarto is a board game for two players invented by Swiss mathematician Blaise Müller.It is played on a 4×4 board. There are 16 unique pieces, each of which is either:* tall or short;...
, Gobblet
Gobblet
Gobblet is a board game for two players designed by Thierry Denoual and published in 2001 by Gigamic and Blue Orange Games. Gobblet was a finalist for the 2004 Jeu de l'année....
. Generalizing the original Tic-tac-toe game, we get the
-game, played on the -dimensional cube with edge . Then, the ordinary Tic-tac-toe is the -game. The m,n,k-games are a family of generalized gameGeneralized game
In computational complexity theory, a generalized game is a game that has been generalized so that it can be played on a board of any size. For example, generalized chess is the game of chess played on an n-by-n board, with 2n pieces on each side.Complexity theory studies the asymptotic difficulty...
s based on tic-tac-toe.
- 3-dimensional tic-tac-toe on a 3×3×3 board, though the first player has an easy win by playing in the centre if 2 people are playing. Another variantQubicQubic is the brand name of a four-in-a-row game played in a 4×4×4 matrix sold by Parker Brothers starting in 1953. The original box, and the 1972 reissue, described the game as "Parker Brothers 3D Tic Tac Toe Game." Players take turn placing pieces to get four in a row horizontally or...
is played on a 4×4×4 board, though it was solved by Oren PatashnikOren PatashnikOren Patashnik is a computer scientist. He is notable for co-creating BibTeX, and co-writing Concrete Mathematics: A Foundation for Computer Science...
in 1980 (the first player can force a win). A more complex variant can be played on boards utilising higher dimensional space, most commonly 4 dimensions in a 3×3×3×3 board. In such games the aim is to fill up the board and get more rows of three in total than the other player or to play with 4 people and get 1 row of 3. - In misère tic-tac-toe the player wins if the opponent gets n in a row. A 3×3 game is a draw.
- Tic Tac Tactic: A new game played on a three-dimensional board. Each player takes it in turns to send their ball at least half way round the curved board until it drops down into one of the 9 indents of the 3 x 3 grid. The player wins balls by forming a row of 3, and they can, using a rubber device, change the outcome of their ball's path and bounce their ball to where they want. Each 3-in-a-row wins a ball of the player. The winner is skilful enough to have won five balls off his opponent.
- In nine board tic-tac-toe nine tic-tac-toe boards are themselves arranged in a 3×3 grid. The first player's move may go on any board; all moves afterwards are placed in the empty spaces on the board corresponding to the square of the previous move (that is, if a move were in the upper-left square of a board, the next move would take place on the upper-left board). If a player cannot move because the indicated board is full, the next move may go on any board. Victory is attained by getting 3 in a row on any board. This makes the game considerably longer and more involved than tic-tac-toe, with a definite opening, middle game and endgame.
- super tic-tac-toe is played like nine board tic-tac-toe except that the game does not end when a player wins a game on one of the small boards. Instead, the position of the small board where that player won is marked on a 3x3 grid, and a player wins when they form 3-in-a-row on that grid.
- In Tic-Tac-Chess, players play a game of chessChessChess is a two-player board game played on a chessboard, a square-checkered board with 64 squares arranged in an eight-by-eight grid. It is one of the world's most popular games, played by millions of people worldwide at home, in clubs, online, by correspondence, and in tournaments.Each player...
and tic-tac-toe simultaneously. When a player captures an opponent's piece, the player can make a play on the tic-tac-toe board regardless if the other player has not yet made a play. The first person to get 3 X's or O's in a row wins the game. This makes for a much more defensive game of chess. - There is a game that is isomorphic to tic-tac-toe, but on the surface appears completely different. Two players in turn say a number between one and nine. A particular number may not be repeated. The game is won by the player who has said three numbers whose sum is 15. Plotting these numbers on a 3×3 magic squareMagic squareIn recreational mathematics, a magic square of order n is an arrangement of n2 numbers, usually distinct integers, in a square, such that the n numbers in all rows, all columns, and both diagonals sum to the same constant. A normal magic square contains the integers from 1 to n2...
shows that the game exactly corresponds with tic-tac-toe, since three numbers will be arranged in a straight line if and only if they total 15. This can be helpful in programming computer adaptations of the game, by assigning the squares of the grid to their corresponding number on the magic square. - Two players fill out a 3×3 grid with numbers one through nine in order of priority. They then compare their grids and play tic-tac-toe by filling in the squares by the priority they listed before.
- In the 1970s, there was a two player game made by Tri-ang Toys & Games called Check Lines, in which the board consisted of eleven holes arranged in a geometrical pattern of twelve straight lines each containing three of the holes. Each player had exactly five tokens and played in turn placing one token in any of the holes. The winner was the first player whose tokens were arranged in two lines of three (which by definition were intersectingLine-line intersectionIn Euclidean geometry, the intersection of a line and a line can be the empty set,a point, ora line. Distinguishing these cases, and finding the intersection point have use, for example, in computer graphics, motion planning, and collision detection....
lines). If neither player had won by the tenth turn, subsequent turns consisted of moving one of one's own tokens to the remaining empty hole, with the constraint that this move could only be from an adjacentAdjacentAdjacent is an adjective meaning contiguous, adjoining or abuttingIn geometry, adjacent is when sides meet to make an angle.In graph theory adjacent nodes in a graph are linked by an edge....
hole. - Toss AcrossToss acrossToss Across is a game first introduced in 1969 by the now defunct Ideal Toy Company. The game was designed by Marvin Glass and Associates and created by Hank Kramer, Larry Reiner and Walter Moe, and is now distributed by Mattel. It is a game in which participants play tic-tac-toe by lobbing small...
is a tic-tac-toe game where players throw bean bags at a large board to mark squares. - Star Tic Tac Toe is tic-tac-toe game where it is played with checkers like movable pieces on 3×3 board. Each player gets 3 pieces.The players move the pieces into empty cells until someone wins. This adds dynamism. In addition each player gets a special piece marked with a star. The stars can be swapped. This adds surprise.
- MojoMojo (board game)Mojo is a two-player, 3 in-a-row abstract strategy board game played with original and unique "thrice-sliced-dice". The pieces, hand-made to order in India, are colored with non-toxic vegetable dye. The individual opposite ends of the pieces are marked with pips and numbered similar to regular...
, Mojo Too and Mojo 2 is a tic-tac-toe game played on a 3×3 board with original and unique movable pieces and pawns - the latter is played for points. The players move the pieces and pawn(s) onto empty positions until someone wins. - The object of the fictional D'ni game of Gemedet is to get six balls in-a-row in a 9×9×9 cube grid.
- The object of the fictional game Squid-Tac-Toad is to get four (or five) pieces in-a-row on a 4×4 or 5×5 checkerboard grid.
- Some children play where getting a Y formation also counts as a win. This effectively guarantees a win, since all of the game scenarios feature some form of Y formation.
- Quantum tic tac toeQuantum tic tac toeQuantum tic-tac-toe is a "quantum generalization" of tic-tac-toe in which the players' moves are "superpositions" of plays in the classical game...
allows players to place a quantum superposition of numbers on the board, i.e. the players' moves are "superpositions" of plays in the original classical game. This variation was invented by Allan Goff of Novatia Labs. - Another variation on tic-tac-toe is played on a larger grid (say 10x10) where the object is to get 5 in a row. The increased amount of space creates a greater complexity.
- There is a variation on tic-tac-toe that is popular in Vietnam, in which the player has to get 5 in a row to win the game. Each player takes turns to mark "x" or "o" on the board. The strategy is to not only block the opponent, but create chances for yourself to form 5 in a row in any direction. The board is unlimited and has no boundary until one wins. See Go-moku
- The game can also be varied by limiting the number of pieces and then allowing movement. The three-a-side then becomes Three Men's Morris (see Nine Men's MorrisNine Men's MorrisNine Men's Morris is an abstract strategy board game for two players that emerged from the Roman Empire. The game is also known as Nine Man Morris, Mill, Mills, Merels, Merelles, and Merrills in English....
). - There is a variation using a list of the words eat, an, laf, it, line, if, lot, on and foe. To win, a player must select three words with the same letter. If the words are plotted on a tic-tac-toe grid in order a three in a row line wins.
- Memory tic-tac-toe is played with the same rules as standard tic-tac-toe. However, instead of marking moves on a piece of paper, the games is played verbally, with each player calling out which locations they take. The most used naming convention is referring to the locations as points as their corresponding cardinal and ordinal pointsCardinal directionThe four cardinal directions or cardinal points are the directions of north, east, south, and west, commonly denoted by their initials: N, E, S, W. East and west are at right angles to north and south, with east being in the direction of rotation and west being directly opposite. Intermediate...
with ″center" referring to the middle piece. In addition to the standard win condition, an optional lose condition may be implemented for a player that "re-touches" an already occupied square. Due to both players trying to keep all the board positions in memory, it may be useful for a third person keep track of the game on paper out of view of the players.
Alternative English names
The game has a number of alternative English names.- Tick-tack-toe, tic-tac-toe, tick-tat-toe, or tit-tat-toe (USAUnited StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
, CanadaCanadaCanada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
) - Noughts and crosses or Naughts and crosses (Great BritainGreat BritainGreat Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...
, Republic of IrelandRepublic of IrelandIreland , described as the Republic of Ireland , is a sovereign state in Europe occupying approximately five-sixths of the island of the same name. Its capital is Dublin. Ireland, which had a population of 4.58 million in 2011, is a constitutional republic governed as a parliamentary democracy,...
, AustraliaAustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, New ZealandNew ZealandNew Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, South AfricaSouth AfricaThe Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
) - Exy-Ozys, Xsie-Osies (verbal name only) (Northern IrelandNorthern IrelandNorthern Ireland is one of the four countries of the United Kingdom. Situated in the north-east of the island of Ireland, it shares a border with the Republic of Ireland to the south and west...
) - Xs and Os (EgyptEgyptEgypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...
, Republic of IrelandRepublic of IrelandIreland , described as the Republic of Ireland , is a sovereign state in Europe occupying approximately five-sixths of the island of the same name. Its capital is Dublin. Ireland, which had a population of 4.58 million in 2011, is a constitutional republic governed as a parliamentary democracy,...
, CanadaCanadaCanada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, ScotlandScotlandScotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
, ZimbabweZimbabweZimbabwe is a landlocked country located in the southern part of the African continent, between the Zambezi and Limpopo rivers. It is bordered by South Africa to the south, Botswana to the southwest, Zambia and a tip of Namibia to the northwest and Mozambique to the east. Zimbabwe has three...
, IndiaIndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
) - O-X (MauritiusMauritiusMauritius , officially the Republic of Mauritius is an island nation off the southeast coast of the African continent in the southwest Indian Ocean, about east of Madagascar...
)
In the United States, the name "noughts and crosses" is not well understood, as the word "nought" is archaic in usage and X-shaped objects are not generally called crosses except in the case of specific named crosses like St. Patrick's Cross.
Sometimes, the games Tic-tac-toe (where players keep adding "pieces") and Three Men's Morris (where pieces start to move after a certain number have been placed) are confused with each other.
In popular culture
In the 1983 film WarGamesWarGames
WarGames is a 1983 American Cold War suspense/science-fiction film written by Lawrence Lasker and Walter F. Parkes and directed by John Badham. The film stars Matthew Broderick and Ally Sheedy....
, tic-tac-toe is used as an allegory for nuclear war
Nuclear warfare
Nuclear warfare, or atomic warfare, is a military conflict or political strategy in which nuclear weaponry is detonated on an opponent. Compared to conventional warfare, nuclear warfare can be vastly more destructive in range and extent of damage...
. In the climax of the film, the protagonist prevents an out of control military defense computer from launching nuclear missiles by making it repeatedly play tic-tac-toe against itself. After quickly learning that good strategy by both players produces no winner, the computer then plays through all known nuclear strike scenarios, again finding no winner. The computer concludes, "Strange game. The only winning move is not to play."
Various game show
Game show
A game show is a type of radio or television program in which members of the public, television personalities or celebrities, sometimes as part of a team, play a game which involves answering questions or solving puzzles usually for money and/or prizes...
s have been based on Tic-Tac-Toe and its variants:
- On Hollywood SquaresHollywood SquaresHollywood Squares is an American panel game show in which two contestants play tic-tac-toe to win cash and prizes. The "board" for the game is a 3 × 3 vertical stack of open-faced cubes, each occupied by a celebrity seated at a desk and facing the contestants...
, nine celebrities filled the cells of the tic-tac-toe grid; players put symbols on the board by correctly agreeing or disagreeing with a statement the celebrity makes. - In Tic-Tac-DoughTic-Tac-DoughTic-Tac-Dough is an American television game show based on the pen-and-paper game of tic-tac-toe. Contestants answer questions in various categories to put up their respective symbol, X or O, on the board. Three versions were produced: the initial 1956–59 run on NBC, a 1978–1986 run initially on...
, players put symbols up on the board by answering questions in various categories. - In Beat the TeacherBeat the TeacherBeat the Teacher was a British game show devised by Clive Doig, made by BBC Television and shown as part of Children's BBC on weekdays at teatimes.-Show format:Each edition featured two contestants; one a school student and the other a teacher...
, contestants answer questions to win a turn to influence a tic-tac-toe grid. - On The Price Is RightThe Price Is RightThe Price Is Right is a television game show franchise originally produced by Mark Goodson and Bill Todman, and created by Bob Stewart, and is currently produced and owned by FremantleMedia. The franchise centers on television game shows, but also includes merchandise such as video games, printed...
, several national variants feature a pricing game called "Secret X," in which players must guess prices to win Xs to place on a blank board. They must place the Xs in position to guess the location of the titular "secret X" hidden in the center column of the board and form a tic-tac-toe line across. There are no Os in this variant of the game. - On Minute to Win ItMinute to Win ItMinute to Win It is an American prime time game show on NBC hosted by Guy Fieri. Contestants take part in a series of 60-second challenges that use objects that are commonly available around the house....
, the game Ping Tac Toe has one contestant playing the game with nine water-filled glasses and white and orange ping-pong balls, trying to get three in a row of either color. They must alternate colors after each successful landing and must be careful not to block themselves.