Tic-Tac-Toe variants are alternative versions of the classic game that introduce new rules or board configurations. Some popular variants include 3D Tic-Tac-Toe, played on multiple layers, and Ultimate Tic-Tac-Toe, where each square contains its own mini-game. These variations can enhance strategy and complexity, making the game more engaging. Another interesting variant is Misère Tic-Tac-Toe, where the objective is to avoid getting three in a row. Players must think differently, as traditional winning strategies no longer apply. These variants provide fresh challenges and can be enjoyed by players of all ages, promoting critical thinking and problem-solving skills.