Frequently Asked Questions
Which difficulty should I start with?
If you are new to Sudoku, start with "Beginner" mode. As you get comfortable, gradually increase the difficulty. The differences are in the number of starting clues and the complexity of techniques required.
What happens when I make a mistake?
You can make up to 3 mistakes before the game ends. Mistaken cells are highlighted in red — entering the correct number clears the error. Your mistake count is shown in the top-right corner.
When does the timer run?
The timer starts automatically when you begin a puzzle and runs until you solve it or the game ends. You can pause with the pause button. Progress is auto-saved if you close the page.
Does every puzzle have a unique solution?
Yes. Every puzzle on Sudoku Dojo has been algorithmically verified to have a single unique solution. All puzzles can be solved through logical deduction — no guessing required.
Tips for a high score?
Your score is based on completion time. Finish with zero mistakes for a bonus, and zero hints for an additional bonus. Try the daily challenge to aim for top scores!
Do I need to play every day?
There is no obligation, but one puzzle a day is the most effective habit. Playing daily steadily builds pattern recognition and logical thinking. The daily challenge resets every 24 hours.
What if I cannot solve a difficult puzzle?
Take a break and come back with fresh eyes. Use the memo feature to organize candidates, or learn new techniques from the solving guide and technique pages.
Can I play on my phone?
Yes. Sudoku Dojo works on all screen sizes — smartphones, tablets, and desktops. Just open your browser; no app download needed.
How do I use the memo feature?
Tap the "Memo" button in the toolbar to enter note mode. Then tap numbers to write small candidate marks in the selected cell. Tap "Memo" again to return to normal input mode.
Is there a difference between Sudoku and ナンプレ?
They are exactly the same puzzle. "Sudoku" is the global name. "Nanpure" is a Japanese nickname coined by Nikoli, derived from "Sūji wa dokushin ni kagiru" (numbers must be single).