Tic Tac Toe

Tic Tac Toe is the classic 3×3 line game for two players sharing one device. X always opens, players alternate, and the first to line up three of their marks horizontally, vertically or diagonally wins. If all nine squares fill with no line, it is a draw.

Every square is a tap: tap an empty cell and your mark appears immediately, then the turn passes. Occupied squares are disabled, and once a winner is decided the whole board locks until you reset.

This version is a pure local two-player board — there is no computer opponent and no difficulty setting. That makes it a clean way to demonstrate why the game is solved: with best play from both sides, X cannot force a win and every game ends in a draw. The interesting part is not winning but spotting the fork — a move that creates two separate winning threats at once, which the opponent can only answer once.