Arcade · 1952 to 1983
Tic-Tac-Toe
One of the first games ever played on a computer, against an opponent that never loses at Impossible. Or set it to zero players and watch the machine play itself.
> YOUR MOVE.
How to play
- Get three in a row, across, down or diagonally. X always goes first.
- Tap a square, or press 1–9: the keys match a numeric keypad, so 7 is top left and 3 is bottom right. N starts a new game.
- Easy and Normal make mistakes you can catch. Impossible plays perfectly, so the best you can do is a draw.
- 0 players hands the board to the machine, which plays itself until it runs out of reasons to.
History
In 1952, A. S. Douglas wrote OXO for the EDSAC computer at the University of Cambridge while he was a PhD student there. It was one of the first games played on a computer: you dialed your move with a telephone dial and watched the board on a small dot-matrix screen.1
Thirty years later, the 1983 film WarGames gave tic-tac-toe a starring role: a military computer, set to play the game against itself, learns that some games can't be won.2 Zero-player mode here is a small tribute to that scene.
Sources
- 1Computer History Museum, “1952: Alexander Douglas writes OXO for EDSAC,” Timeline of Computer History, n.d., https://www.computerhistory.org/timeline/1952/ (accessed October 26, 2026).
- 2American Film Institute, “WarGames (1983),” AFI Catalog of Feature Films, n.d., https://catalog.afi.com/Catalog/moviedetails/67139 (accessed October 26, 2026).
About this version
Rebuilt from the tic-tac-toe in my DOPR-80 page, a WarGames-style 1980s terminal. The computer uses minimax, looking at every possible game to the end, which tic-tac-toe is small enough to allow. At Impossible it has been checked against every possible way to play, as X and as O, and never loses. Your scores and any game in progress are saved in this browser.
A tribute to WarGames (1983); not affiliated with or endorsed by MGM.