Mathematicians have proven that Sudoku requires at least 17 cues to have a unique solution. Sudoku 17 collects all the hardest game levels, with a total of 49,151 levels, all with only 17 tips. For players who like challenges, this will be a very good experience. Sudoku 17 is not a game for novices, it is a very difficult game. If you think you have enough logical reasoning, try the hardest Sudoku.