Clueless Sudoku 1
Clueless Sudoku is made up with nine nonoverlap 9*9 Sudokus.The 10th 9*9 Sudoku is hidden in the topic and marked with dark gray grids.
Sudokus that no one can solve
Sudokus that no one can solve, not only including Sodukus which is very difficult but also that no one trying to solve it.