The 9x9 board shows a Sudoku solution (i.e., each row, file and each of the nine 3x3 squares contains all nine digits 1,2,3,...,9).
Click an arrow to randomize the position.
Then click an arrow to reverse the order in a row or file.
In the default variant you win if you can recreate the original position or create a new Sudoku solution.
(You can open a second Sudoxu window with the starting position and use it as a template).

Variant 4: Here you are not given the solution to the Sudoku puzzle, only a scrambled version of it.
Your goal is to create a Sudoku solution (each row, file and each of the nine 3x3 squares must each contain all nine digits 1,2,3,...,9.)

 
Please note that there are three piece sets available.