Dictionary Definition
ticktacktoe n : a game in which two players
alternately put crosses and circles in one of the compartments of a
3by3 board; the object is to get a row of three crosses or three
circles before the opponent does [syn: ticktacktoe, ticktacktoo, tictactoe,
tittattoe,
noughts
and crosses]ticktacktoe n : a game in which two players
alternately put crosses and circles in one of the compartments of a
3by3 board; the object is to get a row of three crosses or three
circles before the opponent does [syn: ticktacktoo, ticktacktoe,
tictactoe,
tittattoe,
noughts
and crosses]
User Contributed Dictionary
English
Noun
ticktacktoeExtensive Definition
Tictactoe, also called noughts and crosses,
hugs and kisses, and many other names, is a pencilandpaper
game for two players, O and X, who take turns marking the
spaces in a 3×3 grid. The player who succeeds in placing
three respective marks in a horizontal, vertical or diagonal row
wins the game. This game is won by the first player, X:
This is a "cat's game", that is, a draw:
Players soon discover that best play from both
parties leads to a draw. Hence, tictactoe is most often played by
very young children; when they have discovered an unbeatable
strategy they move on to more sophisticated games such as dots and
boxes. This reputation for ease has led to casinos offering gamblers the
chance to play tictactoe against trained chickens.
The simplicity of tictactoe makes it ideal as a
pedagogical tool for teaching the concepts of combinatorial
game theory and the branch of artificial
intelligence that deals with the searching of game trees. It
is straightforward to write a computer
program to play tictactoe 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.
The first known video game,
OXO (or Noughts
and Crosses, 1952) for the EDSAC computer played
perfect games of tictactoe against a human opponent.
One example of a TicTacToe playing computer is
the Tinkertoy computer, developed by
MIT students, and made out of Tinker Toys. It
only plays TicTacToe, and has never lost a game. It is currently
on display at the
Museum of Science, Boston.
Number of possible games
Despite its apparent simplicity, it requires some complex mathematics to determine the number of possible games. This is further complicated by the definitions used when setting the conditions.Simplistically, there are 362,880 (ie. 9!) ways
of placing Xs and Os on the board, without regard to winning
combinations.
When winning combinations are considered, there
are 255,168 possible games. Assuming that X makes the first move
every time:
 131,184 finished games are won by (X)

 1,440 are won by (X) after 5 moves
 47,952 are won by (X) after 7 moves
 81,792 are won by (X) after 9 moves
 77,904 finished games are won by (O)

 5,328 are won by (O) after 6 moves
 72,576 are won by (O) after 8 moves
 46,080 finished games are drawn
Ignoring the sequence of Xs and Os, and after
eliminating symmetrical outcomes (ie. rotations and/or reflections
of other outcomes), there are only 138 unique outcomes. Assuming
once again that X makes the first move every time:
 91 unique outcomes are won by (X)

 21 won by (X) after 5 moves
 58 won by (X) after 7 moves
 12 won by (X) after 9 moves
 44 unique outcomes are won by (O)

 21 won by (O) after 6 moves
 23 won by (O) after 8 moves
 3 unique outcomes are drawn
Strategy
A player can play perfect tictactoe if they
choose the move with the highest priority in the following
table.
 Win: complete three in a row.
 Block: block their opponent from completing three in a row
 Fork: threaten a win with two possible completions in two ways
 Block Fork:
 Option 1: create two in a row to force a block (Note: Sometimes, if one forces a block in this manner, the other player's block will result in a fork and a winning position, so care must be taken when there is more than one way to create two in a row. For example, if X has played the center and a corner, and o is in the opposite corner, o must play a corner and not an edge or else x will win).
 Option 2: if there is a configuration where the opponent can fork, block that fork
 Centre: play the centre
 Opposite Corner: if the opponent is in the corner, play the opposite corner
 Empty Corner: play an empty corner
 Empty Side: play on an empty side
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 ninarow: three men's morris, nine men's morris, pente, gomoku, Qubic, Connect Four, Quarto, Gobblet. The m,n,kgames are a family of generalized games based on tictactoe. 3dimensional tictactoe on a 3×3×3 board, though the first player has an easy win by playing in the centre. Another variant is played on a 4×4×4 board though it was solved by Victor Allis in 1994 (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.
 4 player 3dimensional tictactoe: Not as easy to win by the first player, the symbols are O's X's triangles and squares, otherwise the rules to 3D tictactoe apply.
 In misère tictactoe you win if the other player gets n in a row. The 3×3 game is a draw.
 In nine board tictactoe nine tictactoe 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 upperleft square of a board, the next move would take place on the upperleft board). If a player can't 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 tictactoe, with a definite opening, middle game and endgame.
 In TicTacChess, players play a game of chess and tictactoe simultaneously. When a player captures an opponent's piece, the player can make a play on the tictactoe 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 tictactoe, 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 square shows that the game exactly corresponds with tictactoe, since three numbers will be arranged in a straight line if and only if they total 15.
 Two players fill out a 3×3 grid with numbers one through nine in order of priority. They then compare their grids and play tictactoe by filling in the squares by the priority they listed before.
 In the 1970s, there was a two player game made by Triang 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 intersecting 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 adjacent hole.
 Toss Across is a tictactoe game where players throw bean bags at a large board to mark squares.
 Various game shows have
been based around the game:
 On Hollywood Squares nine celebrities filled the cells of the tictactoe grid.
 In Secret "X", a pricing game on The Price is Right, contestants must get three Xs in a row by correctly pricing items, and then find the one X in the middle column to complete a line.
 In TicTacDough players put symbols up on the board by answering questions in various categories.
 In Beat the Teacher contestants answer questions to win a turn to influence a tictactoe grid.
 The object of the fictional D'ni game of Gemedet is to get six balls inarow in a 9×9×9 cube grid.
 The object of the fictional game SquidTacToad is to get four (or five) pieces inarow on a 4×4 or 5×5 checkerboard grid.
 Some children play where getting a Y formation also counts as a win.
 Quantum tic tac toe allows players to place a quantum superposition of numbers on the board
 Another variation on tictactoe 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.
 Another variation on tictactoe that is popular in Vietnam that the player has to get 5 in a row to win the game. It's called CroaZero (not sure if this is the correct spelling  could be CrossZero. Each player takes turn to mark "x" and "o" on the board. The stategy is to not only blocking the opponent, but creating chances for yourself to form 5 in a row in any direction. The board is unlimited and has no boundary until one wins.
Alternative names
Around the world, the game has a number of alternative names. Tictactoe, ticktattoe, or tittattoe (USA , Canada)
 Noughts and crosses or naughts and crosses (United
Kingdom, Ireland, Australia,
New
Zealand, South
Africa)
 "Noughts and crosses" is a sensibly descriptive name for the game, except in the United States, where "nought" is regarded as an archaism and where a lone "x" is not generally referred to as a "cross".
 Kringetjies en Kruisies (South Africa)
 Kaat koot or Zerokata (Hinglish  India)
 Katam kataa (Hindi  India)
 Ix Igul (X Circle) (Israel)
 Kata kuti (Bangladesh and West Bengal)
 Phulli Gola (Marathi)
 ExyOzys, XsieOsies (verbal name only) (Northern Ireland)
 Boxin' OXen (Republic of Ireland)
 X's and O's (Republic of Ireland) , Canada, (Dundee,Scotland)
 Teetaatoe (Jamaica)
 X si O (Romania)
 Amőba (Hungary)
 Luffarschack (Sweden)
 Jogo do Galo (meaning "Rooster's Game") (Portugal)
 Jogo da Velha (meaning "Old Lady's Game") (Brazil)
 Tris, filetto, crocetta e pallino, cerchi e croci, or tria (Italy)
 Kółko i krzyżyk (a circle and a cross) (Poland)
 Boter, kaas en eieren (Butter, cheese, and eggs) (Netherlands)
 Morpion (France)
 Tres en raya (Spain and Ecuador)
 Gato (Chile, México and Costa Rica)
 IksOks (Serbia and Mongolia)
 Križićkružić (a circle and a cross) (Croatia)
 Kaat kar ya Zero Pa (UPunjabi  Pakistan)
 Michi (Perú)
 Križci in krožci (crosses and circles) (Slovenia)
 Крестикинолики (crosses and zeroes) (Russia)
 Морски шах (sea chess) (Bulgaria)
 TaTeTi (Argentina)
 Τρίλιζα (Triliza) (Greece)
 X ṣi Zero (Romania)
 X O (Iran, Egypt, Arabic Speaking Countries)
 Cüz (Turkey)
 Bondesjakk (farmer's chess) (Norway)
 La Vieja (Venezuela)
 Piškvorky (Czech Republic and Slovakia)
 Triqui (Colombia)
 Bicho Chocha (XO)(Mexico)
 دووز (Iran)
 Ristinolla(crosszero) or Jätkänshakki((Finland)
 Equis Cero (XO) (Dominican Republic)
 Tripstrapstrull (Estonia)
 X Mix Drix (Israel)
 Kryds og Bolle (Cross and buns) (Denmark)
 Deppenschach (Austria)
 CroaZero (Vietnam)
 CrossZero (Vietnam)
 圓圈交叉 (circlecross), 井字過三關 (Hong Kong)
 Mylla (mill) (Iceland)
 Desas (Sausages) (Latvia)
Sometimes, the names of the games Tictactoe
(where players keep adding "pieces") and Three
Men's Morris (where pieces start to move after a certain number
have been placed) are confused.
In fiction
In the 1983 film WarGames,
tictactoe is used as an allegory for nuclear
war.
In the film, teenage computer hacker David
Lightman (Matthew
Broderick) unknowingly breaks into the United States' defense
computer, WOPR, where he
innocently starts a game of "Global Thermonuclear War". This
triggers a sequence of events that eventually leads to the computer
preparing to launch actual nuclear missiles. Lightman eventually
influences the computer to play tictactoe against itself, whereby
the computer determines that neither side can win–an analogy to
full scale nuclear
war, which is made explicit when the computer then fails to
find a winning stratagem for a nuclear strike. The computer then
concludes that "[t]he only winning move is not to play" and
indicates a desire for a game of chess instead.
References
External links
 Wolfram's MathWorld
 Ostermiller.org TicTacToe strategy guide
 How many TicTacToe games are possible?
 Tic Tac Toe Extreme (Multiplayer Tic Tac Toe)
 A free TicTacToe game online
 Multi TicTacToe Games 3x3, 4x4, 6x6
 ChessandPoker.com stepbystep strategy guide for both players
 PDF of "How to Win at TicTacToe"
 Demonstration of isomorphism between TicTacToe and 'Game of 15'
 iPod TicTacToe.
 Where does tic tac toe come from?
 New 5x5x5 3D TTT PC Game!
 Wicked TicTacToe
ticktacktoe in Belarusian (Tarashkevitsa):
Крыжыкінулікі
ticktacktoe in Catalan: Tres en ratlla
ticktacktoe in Czech: Piškvorky
ticktacktoe in Danish: Kryds og bolle
ticktacktoe in German: Tic Tac Toe
ticktacktoe in Spanish: Tres en raya
ticktacktoe in French: Morpion (jeu)
ticktacktoe in Galician: Pai fillo nai
ticktacktoe in Korean: 틱택토
ticktacktoe in Croatian: Kružić i križić
ticktacktoe in Italian: Tris (gioco)
ticktacktoe in Hebrew: איקס עיגול
ticktacktoe in Latin: Cruces et circuli
ticktacktoe in Lithuanian:
Kryžiukainuliukai
ticktacktoe in Dutch: Boter, kaas en
eieren
ticktacktoe in Japanese: 三目並べ
ticktacktoe in Polish: Kółko i krzyżyk
ticktacktoe in Portuguese: Jogo da velha
ticktacktoe in Russian: Крестикинолики
ticktacktoe in Serbian: Иксокс
ticktacktoe in Finnish: Ristinolla
ticktacktoe in Swedish: Tic Tac Toe
ticktacktoe in Thai: โอเอกซ์
ticktacktoe in Vietnamese: Tictactoe
ticktacktoe in Chinese: 井字過三關