Your goal is to win the 2D Tic Tac Toe by winning 3 linked smaller Tic Tac Toes. Once you win a small Tic Tac Toe, you win the box at the 2D level. You have to win 3 linked boxes at the 2D level to win the game.
You can play the game at 3 different levels. At level 1, there are no restrictions for your next move. You can make your move at any empty cell. The excitement begins at level 2 which your location at the 1D level decides the location at the 2D level. At level 3, you decide your opponents next move at the 2D level. Your location at the 1D is your opponents next location at the 2D level.
When all cells in a 1D Tic Tac Toe are filled up, you will be allowed to pick any empty cell at the 2D level. This is where the strategies begin.