Blocking an opponent's fork: If there is only one possible fork for the opponent, the player should block it.Fork: Cause a scenario where the player has two ways to win (two non-blocked lines of 2).Block: If the opponent has two in a row, the player must play the third themselves to block the opponent.Win: If the player has two in a row, they can place a third to get three in a row.Player O can only force a win or draw by playing in the centre first.Ī player can play a perfect game of tic-tac-toe (to win or at least draw) if, each time it is their turn to play, they choose the first available move from the following list, as used in Newell and Simon's 1972 tic-tac-toe program. 3 distinct positions are drawn (often called a 'cat's game' ).

A combinatorics study of the game shows that when 'X' makes the first move every time, the game outcomes are as follows: rotations and reflections), there are only 138 terminal board positions. When considering only the state of the board, and after taking into account board symmetries (i.e. It is currently on display at the Museum of Science, Boston. The Tinkertoy computer, made out of (almost) only Tinkertoys, is able to play tic-tac-toe perfectly. In 1975, tic-tac-toe was also used by MIT students to demonstrate the computational power of Tinkertoy elements. The computer player could play perfect games of tic-tac-toe against a human opponent. In 1952, OXO (or Noughts and Crosses), developed by British computer scientist Sandy Douglas for the EDSAC computer at the University of Cambridge, became one of the first known video games. The US renaming of 'noughts and crosses' to 'tic-tac-toe' occurred in the 20th century. 'Tic-tac-toe' may also derive from 'tick-tack', the name of an old version of backgammon first described in 1558. 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 of trying with the eyes shut to bring the pencil down on one of the numbers of a set, the number hit being scored'.

The first print reference to 'noughts and crosses' ( nought being an alternative word for 'zero'), the British name, appeared in 1858, in an issue of Notes and Queries. The different names of the game are more recent. Another closely related ancient game is three men's morris which is also played on a simple grid and requires three pieces in a row to finish, and Picaria, a game of the Puebloans. The game's grid markings have been found chalked all over Rome. It was called terni lapilli ( three pebbles at a time) and instead of having any number of pieces, each player had only three thus, they had to move them around to empty spaces to keep playing. Īn early variation of tic-tac-toe was played in the Roman Empire, around the first century BC. Games played on three-in-a-row boards can be traced back to ancient Egypt, where such game boards have been found on roofing tiles dating from around 1300 BC. Tic-tac-toe's incidence structure consists of nine points, three horizontal lines, three vertical lines, and two diagonal lines, with each line consisting of at least three points. It can be generalised even further by playing on an arbitrary incidence structure, where rows are lines and cells are points. It can also be generalized as an n d game, specifically one in which n equals 3 and d equals 2. Harary's generalized tic-tac-toe is an even broader generalization of tic-tac-toe. 2 player hockey games online free.The game can be generalized to an m, n, k-game, in which two players alternate placing stones of their own color on an m-by- n board with the goal of getting k of their own color in a row.

Tic tac tiles