To play
Royal sudoku
If you like Sudoku but you're tired of always the same, here's an improved version where you have to squeeze your brain to solve this incredible Sudoku. The first difficulty is that instead of having 9 squares each box is 16, and if that's not enough you can choose from three options, only numbers, only letters, or a perfect combination of numbers and letters.
SudokuControls :
RATON