Variants of tic tac toe
The following variations of rules can be used when playing tic tac toe.
Three piece variant.
Instead of placing a mark alternating each players gets only three marks to place. After placing the third marker instead of adding another marker on of the old markers is replaced. This is actually the style in which the romans played it and gives more dept to the game.
Multi square variant.
Instead of having a 3x3 grid you have a 4x4 or 5x5 or 6x6 grid and so on. Now the goals is to get 4 in a row respectively 5 and 6 in a row. By grids bigger then 6x6 i recommend sticking to 5 in a row to keep the game playable and giving it more debt.
3d tic tac toe.
3d tic tac toe is played by having three 3x3 grids on top of each other. This adds an extra dimension to the game along which also three in a row can be formed.
Super tic tac toe.
9 tic tac toe field are placed in a 3x3 grid. Now the on each of the fields the game of tic tac toe is played normally. But now when a player wins that field gets turned to his mark and the goal is to get three in a row on the bigger field with tic tac toe fields.