XOX (Tic-Tac-Toe)
Get three in a row. On Impossible, the computer never loses. A draw is the best you can do.
The starting player alternates every round.
How the unbeatable AI works
On Impossible, the computer uses the minimax algorithm. It plays out every possible future game, assumes you'll always make your best move, and picks the move with the best guaranteed outcome. Tic-tac-toe has fewer than 9! = 362,880 move sequences, so it can search all of them instantly. Perfect play from both sides always ends in a draw.
Tips
- Starting in a corner gives your opponent the most chances to go wrong.
- If your opponent takes a corner first, always answer with the centre.
- Try to create a fork: two winning threats at once, so only one can be blocked.