Boards with fewer obvious steps, suited to players who are comfortable maintaining full Notes and multi-layer reasoning.
9×9 Sudoku board. Use the arrow keys to move between cells; Home and End go to the start or end of a row; Ctrl or Command + Home/End goes to the first/last cell on the board. Keys 1–9 enter a digit in the current mode; Shift + 1–9 adds a quick Note without turning Notes on; 0, Delete, or the numpad decimal key clears a cell; N toggles Notes, A toggles Auto Candidates, and Space pauses the game.
Levels 1–2 only guide you and do not use a hint; level 3 applies the solving step and uses 1 hint.
Select an empty cell to see valid candidates.
Auto candidates and Notes mode are remembered separately for Classic and Killer. Pause state and game progress are not synced as preferences.
At Master level, a correct move often comes from relationships across several regions rather than just one row or block. Speed matters less than maintaining accurate candidates and recognizing verifiable elimination chains.
Difficulty is not assigned from clue count alone. The site grader follows human techniques first, records the hardest technique reached, and uses residual search only when implemented logical techniques stall.
Techniques found: Naked Single · Hidden Single · Locked Candidates
This is one representative verified puzzle from the current verified quality pool. Difficulty remains an estimate because player experience changes how hard the same board feels.
Master Sudoku fits players who are comfortable reasoning across the whole board and can maintain accurate candidates for a long time. Obvious moves are rarer, so one small elimination can unlock several other regions.
Do not skip basic techniques just because the puzzle is difficult. After an elimination chain or advanced pattern, go back to singles, pairs, and intersections; many Master games open up from exactly this kind of rescan.
Master puzzles usually provide fewer obvious entry points and require longer interactions between candidate patterns across the grid. Accuracy matters more than solving speed.
Keep candidates complete and clean. After any major elimination, scan again for singles, pairs and locked candidates because advanced moves often unlock a simpler continuation.
A hint is most useful as a learning tool after you have exhausted the patterns you know. Read the reason for the move, then continue from the new state instead of repeatedly revealing answers.
The game board supports Notes, Undo, Pause, Hints, and saved progress. You can sign in later if you want to sync your achievements.
