Line Three

A closer look at Line Three

A small board with clear rules

You and the computer take turns placing a mark on a three-by-three board. You play X and always go first. The computer plays O. Three matching marks in any row, column, or main diagonal win the round. If all nine squares fill without a winning line, the result is a draw. A mark stays in its chosen square for the entire round.

Check immediate threats first

Before placing X, look for a line that already contains two X marks and one empty square. Completing it wins immediately. If you cannot win this turn, check whether O has the same opportunity and block it. Looking for threats before making a general positional move is a useful habit on this board.

Understand what a fork means

A fork creates two different winning threats at once. Your opponent has only one move, so it cannot normally block both empty winning squares. Corners and the center can participate in several lines, which makes them important when building or preventing forks. Count the actual open lines rather than assuming that any corner move creates a fork.

Why a draw can be a good result

The computer searches the remaining legal moves and chooses a result that avoids losing whenever possible. Because it plays carefully, you should expect draws when you also play well. A draw is not a broken game or a hidden loss. It means both players prevented the other from completing a line before the board filled.

Play and review

Tap a square or focus it with Tab and press Enter. While the computer is choosing its response, new player moves are briefly locked. New puzzle clears the board and gives you the first move again. After each round, trace the lines that were blocked. That review is often more useful than starting another round immediately.