Tic Tac Toe
About This Game
Three in a row against a computer that cannot be beaten, or a friend.
Three in a row, done properly. The computer plays a full minimax search of the game tree with no depth limit, so on Impossible it genuinely cannot be beaten - noughts and crosses is a solved game, and the best anyone can do against perfect play is a draw.
It picks at random between moves that are equally optimal, so it stays unbeatable without becoming predictable. Easy and Medium are the same engine playing its best move only some of the time, which is what a beatable opponent actually looks like - one that makes mistakes, rather than one following a worse rulebook consistently enough for you to read.
There is a two-player mode for the same screen, a running scoreboard, and the opening move alternates every round so nobody keeps the first-move advantage. Marks draw themselves in, the winning three are struck through, and everything is timed against a clock so it looks the same on any monitor.
Tap a square, or use the number keys.
How to Play Tic Tac Toe
- Tap or click a square
- Place your mark.
- 1 to 9
- Place in that square, counting left to right from the top-left.
- R
- Start the next round when one is over.
Rules
- Get three of your marks in a row, column or diagonal. A full board with no line is a draw.
- Against the computer you play X. The first move alternates every round, so you start the first round and the computer the second.
- Three difficulties. Impossible plays a perfect move every time and cannot be beaten. Medium plays its best move about two times in three, Easy about one time in five, and a random move otherwise.
- A two-player mode shares one screen. The running scoreboard of wins and draws is kept on this device.
Tips for Tic Tac Toe
- Against Impossible, a draw is the best possible result. Play the centre or a corner first and block every two-in-a-row.
- On Easy and Medium, set up two threats at once: a mark that makes two lines of two can only be blocked on one of them.
- When the computer moves first and takes a corner, take the centre. A side square there gives it a forced win.
If You Like Tic Tac Toe
- Chess Master – A much deeper board game against an engine with four strength levels.
- Checkers – Draughts against an engine that searches further ahead on each difficulty.