Frequently asked questions about Sudoku
Does every puzzle in the app have only one solution?
Yes. The puzzles that ship with the app, 100 per level, each have a unique solution, rechecked by the app's solver. A puzzle entered in Custom is accepted only if that same solver finds exactly one solution for it.
Does the app tell you when a digit is wrong?
The app accepts any digit and only compares it with the other digits in its row, column and box, never with the solution. With the "Show errors" setting, which is off by default, a conflicting cell is shown in red. When the grid is full but not solved, an "Errors" banner appears, and the button of the same name clears all conflicting digits at once.
How many hints can you ask for?
5 per game. Each hint fills a randomly chosen empty cell with the correct digit, not necessarily the selected cell. The revealed digit is shown in red and can no longer be changed.
Can you undo a move?
There is no undo button. To remove a digit, select the cell and then tap "Erase", or tap the cell twice. The digits given at the start can't be erased.
How many digits are given at the start?
50 on Easy, 40 on Medium, 30 on Hard and 20 on Inhuman. All puzzles of the same level have exactly the same number.
Does the Inhuman level require guessing?
No, every puzzle has a unique solution that can be found by reasoning. Of the 100 Inhuman puzzles, 79 can be finished with singles alone and 87 by adding naked pairs; the others require more advanced techniques.
Can you play a puzzle found elsewhere?
Yes, with Custom: copy in the given digits, at least 17, then confirm. The app looks for the solution; if there is none or more than one, it returns to the entry screen without a message.
What does the Saves screen keep?
The last 20 solved puzzles, with their level and time. You can replay any of them from Saves, except a Custom puzzle.