Pure Sudoku is a free download game. It has four levels of difficulty. Sure enough they are "Very easy", "Easy", "Challenging" and "Hard".You will also see a background with all kinds of pictures. It will take you to the Great Wall and Stonehenge. But the interface is not particularly pretty.But if you are a Sudoku freak, you will not care about that! Right? Do you think you are a Sudoku pro? Want to prove it? Play Pure Sudoku!