For the real Sudoku lovers and smarties (as the creator’s of Kokonotsu call them) there is a website at kokonotsu with every day a new online Super Sudoku Puzzle.
They call the Super Sudoku “Kokonotsu” which is a 9-letter word and meaning “nine” in Japanese. The difference between Kokonotsu and a normal Sudoku is that there is a fourth and fifth dimensions added to the normal Sudoku. Next to the normal numerals 1 through 9 you have to place in each row, column and 3×3 square.
Kokonotsu adds the two major diagonals. Also, there is a Magic Puzzle Heart which enables clever players to solve the puzzles more quickly, plus a unique four-number solution code to quickly check if the puzzle has been correctly solved.
All these extra features add elements of challenge and discovery that are missing in ordinary Sudoku. Happy Puzzling!