rekubus is an interlocking puzzle in the shape of a hollow cube that was invented by Mike Klotzki.
You immediately notice the rather unusual shape of the pieces.
rekubus consists of three different pieces:

8 corner pieces, 12 edge pieces and 6 side parts.
Additionally, there are 12 rails which serve to hold the pieces in place.

To solve the puzzle, it is advisable to build first one side
and then the rails which are only connected by the corner pieces.
The side parts slide over two parallel rails into the middle of the side (see photo)
and are also hold in position by these two parallel rails.
The edge pieces are respectively pulled over two parallel rails and stay attached like a clip.

The charm of this puzzle is to find out how to attach the rails.
The puzzle has a size of 6.5 cm and lies comfortably in the hand.
Moreover, it is very robust so that it can also bear strong loads.
At first glance, it does not seem to be very difficult to put the puzzle together,
as the position of the pieces can be easily recognized.
Nevertheless, logical and three-dimensional intellectual power is needed to attach the trails
and to build the cube bit by bit.

In my point of view, the puzzle is well suited for older kids as well as for adults.
The three-dimensional complexity of the assembly trains logical and analytical thinking
through playing and is at the same time not to difficult to be overwhelmed by the problem.

The speciality and the next challenge of recubus cubes is that any desired number of these cubes
can be linked with each other and put together to three-dimensional figures.
Thereby all parts of the cubes are used. recubus cubes are available in different difficulty levels,
whereby the building principle always is the same. You can choose between different colouring cubes
or six printed cubes whereby the task of the colouring cubes is to rebuilt the design of the cube.
The printed cubes have the further challenge to find the solution for the correct order of the pieces.

In my point of view rekubus is ideal for children from the age of 10 years on as well as for adults.
It is interesting that the cube is hollow. Therefore, it can also be regarded as an interlocking box.

rekubus Devil's Cube shall have 3 x 3 magical squares on all 6 sides.
This means that the sum on each cube side is always the same in the vertical, horizontal and diagonal direction.
The combination of the possible numbers is quite high and seems to be difficult on first glance.

If you look closer at a magical square of the 3 x 3 size,
then you see that the sum along a row/column or diagonal always equals the three time value of the number in the center.

As the six different side parts have different numbers, each magical square has also a different sum per row:


My solution strategy was simply to find a magical square for one side
so that the sum of the numbers on the side edges correspond to the sums of other magical squares.
Under this condition, only two to three magical squares stay in consideration.
As all numbers on the remaining four neighboured sides are known, the non-suited magical squares can be easily excluded.

I would recommend to purchase the rekubus Devil's Cube, as therewith you get two good puzzles at the same time
because of the combination of two tasks: an interlocking puzzle and a magical square.
Concerning the age, I would suggest a lower age limit of 12 years,
as from this age on children are familiar with algebra and thus can solve the puzzle.
Nevertheless, the both more difficult number cubes Devil's Cube and Champion are also interesting for grown-ups.

You can buy the rekubus cubes on the official website.