Ukodus classic
Ukodus – reading sudoku backwards. The diagram is identical to sudoku diagram, but it is completed by digits from the start.
You should cross out digits, so that in horizontal and vertical lines and in every box each digit appears only once.

Ukodus diagonal
In addition, in the diagram digits can’t be repeated at one of the diagonals.

Ukodus X
In addition, digits can’t be repeated in both diagonals.

HyperUkodus
In the diagram 9x9, you can find additional 3x3 four boxes, where digits also can’t be repeated.
Specific method for this kind of Ukodus is about finding digits, which must be put in both overlapping boxes at the same time.