Hard sudoku
| 3 | 6 | 1 | ||||||
| 8 | 6 | 7 | ||||||
| 1 | 8 | 4 | 5 | |||||
| 9 | 4 | 8 | 7 | 5 | ||||
| 6 | 2 | 9 | 3 | |||||
| 2 | 3 | 9 | 8 | |||||
| 6 | 4 | 3 | 8 | |||||
| 9 | 8 | 7 | 6 | |||||
| 5 | 3 |
Fewer numbers again, and longer chains: each number you place opens the way to the next.
- 31 to 35 numbers given
- Solved with singles alone
- One hint per game: it names the technique of the next step and shows why it works.
Techniques you need
How Hard sudoku plays
Hard puzzles give fewer numbers still, and the singles come in longer chains, each placement opening the next. Notes help here, to keep track of where each number can still go.
Learn to solve it
How to Play explains the rules and the singles, and the techniques page shows each technique the hint can name, on a real puzzle.
Your games stay in this browser
The game keeps your games, statistics and settings in this browser, on this device, and sends none of them anywhere. It counts games opened, started and won, with no ID and no cookie, so no count can be tied to you. Another browser starts afresh.
The same game in Telegram
In Telegram the game keeps your progress on all your devices, can remind you of the daily challenge, and lets a group play the daily together, with its standings.
Questions
Is it free?
Yes. There are no ads, no sign-up and nothing to install, and every level is open from the start.
Where is my game saved?
In this browser, on this device: close the page, and the game goes on where you left it. Clearing the browser's data removes it, and so does Safari after seven days without a visit. In Telegram your games follow you to every device.
How does the hint work?
Each game has one hint. It finds the step a person would take next, names its technique and shows on the board why it works, then places the number or removes the notes it rules out.
How do the levels differ?
By the techniques a puzzle needs and the numbers it starts with. Easy to Expert need only the singles, with fewer numbers each time; Master adds pairs, triples and pointing; Extreme needs at least one technique beyond them.