3D Tic Tac Toe is a variant of the 'Naughts and Crosses' game that I like to play with a friend of mine. I prefer to play it on a 4 x 4 x 4 grid rather than a 3 x 3 x 3 grid, but every other rule is the same. I enjoy this because of the many different strategies you can implement, as I had literally come up with a flow chart that makes you un-beatable in the standard 3 x 3 game (you either win or tie, at a 1:2 rate or so)