Tic-Tac-Toe
Two players alternate placing their mark — X or O — on a 3×3 grid. The first to line up three of their marks in a row, column, or diagonal wins. If all nine squares fill without a line, the game is a draw, which happens often once both players know the strong opening moves. Take a corner or the center first, and always block your opponent's two-in-a-row before chasing your own.