At Mathpuzzle dot com you can find Magic Sudoku by Alexandre Owen Muniz.
Magic Sudoku contains only 9 numbers (1 till 9). The rules of standard Sudoku apply: every row, column, and 3×3 square must be filled in with all of the numbers from 1 to 9. But with the following two additional restrictions:
– Both of the main diagonals must also contain every number between 1 and 9.
– Each number inside the polyomino (blue cells) must be no larger than the number of blue cells in its 3×3 square. Conveniently, this number is the given in that 3×3 square.
There is only one unique solution. Download the pdf version of Magic Sudoku (100kb). Happy Puzzling!