The Hardest Sudoku

17 is the minimum number of clues in any proper sudoku (i. e. sudoku with a unique solution). The app contains a database of 50 000 sudokus with only 17 numbers initially. Thus this database includes some of the hardest grids ever, although a lot of grids presented are not that difficult as one may expect. Future selection of the super-hard puzzles is intented (with contribution of solvers using the app). The app offers: simple design and fast interface no ads 50 000 beatiful puzzles This app was made possible thank to Gordon Royle and The University of Western Australia, who collected puzzles with 17 initial values.