Here at Chalkdust HQ, we love inventing ways to make Sudoku-style puzzles more interesting. This week, I will be sharing some 3D puzzles, which I call **Cuboku**.

To build a Cuboku, start with a small Sudoku made of four 2×2 squares as opposed to nine 3×3 squares. To make the visualisation in 3D easier, I will be using four different colours (red, green, blue, yellow) instead of numbers. The usual rules apply: you cannot put the same colour twice in any of the vertical or the horizontal lines or in any of the four 2×2 squares. A completed Sudoku may look like this:

Now, you only have to pile up four of these Sudoku to obtain a cube — except that the slices along each axis also have to satisfy the rules of Sudoku! So you now have to solve 12 (4×3) Sudoku! A completed Cuboku may look like this:

12 Sudoku are formed (the transparent cube has been added to demonstrate how the different slices relate to each other):

Now for the puzzles:

### The First Puzzle

Now that we are all set up with the rules and how to play this fabulous game, let’s start with

the first puzzle: complete the rest of the Cuboku.

Now that you have a little practice solving Cuboku, here’s two more challenging puzzles:

### It’s All About the Corners!

If the vertices of the cube are coloured as below, how many ways are there to complete the rest of the Cuboku?

### Cuboku Counts!

If you begin with the following cubes, how many ways are there to complete the Cuboku?