Strategy
Tic-tac-toe
Three symbols in a row: easy to learn, flawless at Master level.
The most famous of all line-up games. Against the Master level, the best you can hope for is a draw.
- Players
- 1 or 2 players
- Length
- 1 min
- Against the AI
- Two players on one device
15 days of full access, no account · No download
How to play
Goal
Two players take turns placing their symbol, X or O, on a 3 × 3 grid. The first to line up three symbols horizontally, vertically or diagonally wins.
How it works
- X always goes first.
- If the grid fills up with no line, the game is a draw.
- Keys 1 to 9 on the numeric keypad: quick placement.
Tip: the centre and the corners offer the most possible lines. Against the Master level, aim for a draw: the AI calculates every possible game.
About the AI
Exhaustive minimax with alpha-beta pruning. The lower levels deliberately introduce inaccuracies that become less and less frequent.
AI levels
- BeginnerIdeal for learning: plays fast and makes mistakes.
- AmateurKnows the basics, but lets opportunities slip by.
- IntermediateA solid opponent that demands your full attention.
- ExpertCalculates deeply and punishes every mistake.
- MasterNearly unbeatable: the full power of the engine.
