You surely will know the game Tic Tac Toe. It is about pitching first three crosses or circles in a row of a 3 x 3 squares board.

Here comes a three-dimensional version in a cube, in which one has to get four stones in a row. You can
either click directly on the **nodes (!)** of the cube, or of the squares representing the four different levels of the cube.
A row can also be a diagonal in a plane and through the space.

Top left, there is indicated the score of the two players, or of the player and the computer. The game ends when all nodes are
occupied, or when there is no row left to be completed.

Other cube sizes are possible (although of limited use). In cubes with an odd number of nodes, the center node is already occupied
with a black piece which counts for both players. I imagine that otherwise the one who begins will occupy the center field and
then have an advantage.
I don't know whether this is true or not.

Enjoy the game !

Now we go a step further and extend the game to four dimensions !
The playing field is no longer a two-dimensional area of 3 x 3 squares, nor a three-dimensional cube with 4 x 4 x 4 boxes,
but a four-dimensional cube with 5 x 5 x 5 x 5 fields (more precisely, nodes).
It graphically displays five cubes of 5 × 5 × 5, each one shifted by one level into the fourth dimension
(how you imagine such a cube is your thing).

Each of these cubes is also represented by five squares. The tokens can only be set by clicking on the nodes of the squares,
not of the cubes. Overall, our four-dimensional cube has 625 nodes, which is quite a lot.

Nevertheless, have fun playing it !