Variants of Tic-Tac-Toe
There are many games that are very similar to Tic-Tac-Toe.
3D Tic-Tac-Toe: This is Tic-Tac-Toe played on a three-dimensional grid. The game is usually played on a 4 x 4 x 4 board with the first 4-in-a-row win. The brand name for this game is called Qubic.
Ultimate Tic-Tac-Toe: This game involves nine Tic-Tac-Toe games arrange in a 3 x 3 grid. The winner must win the Tic-Tac-Toe in the large 3 x 3 grid. Play here.
Read about other variants of the Tic-Tac-Toe game on Wikipedia here.