Start near the center to build threats in several directions. An open three can become an open four in one move; its three marks may be consecutive or have a gap. An open four, also called a straight four, has four consecutive marks with a winning square at each end. One defensive move cannot block both ends. Check that there is enough space before treating a pattern as a threat.
- If you can complete five in a row this turn, take the win.
- Otherwise, block an immediate winning move; stop an open three before it becomes an open four.
- Create a double threat with two different winning squares that cannot both be blocked in one move.
- Keep space to extend your lines and watch the edges of the board.
Why 10x10 gets interesting
Unlike 3×3 Tic Tac Toe, which needs three in a row, this game needs at least five. The 100-square board gives you room to build combinations, create double threats, and defend in several directions.