3D Tic-Tac-Toe is a space-age version of the classic pen-and-paper game with a twist. Rather than using a single two-dimensional grid consisting of nine squares, 3D Tic-Tac-Toe features four separate 16-square grids stacked on top of each other. The object is to place four X's or four O's in a row, either horizontally, vertically, or diagonally. Furthermore, you can also place four-in-a row in any direction going through the four parallel boards that lie on top of each other on the playing screen.
Players can compete against each other or the computer, with eight different skill levels to choose from. At the most difficult level, the computer may take up to 20 minutes to decide on a move.