Naked single
A cell has just one legal candidate. It is the most direct form of proof and should always be checked before more elaborate patterns.
- Scan a crowded row, column, or box
- List what is missing
- Confirm the crossings
Sudoku solving strategies
Every advanced pattern begins
Every advanced pattern begins
with a clean candidate set.
Sudoku strategies do not replace the classic rules. They are names for repeatable ways to see how rows, columns, boxes, and candidate notes constrain one another. The right first move is still the smallest deduction the board can prove.
12×SINGLE · PAIR · LINE
Hidden single
Several candidates may remain in a cell, but one digit has only one possible home within a row, column, or box. The digit—not the cell—reveals the move.
- Scan one digit through a unit
- Compare its legal homes
- Place it only when one survives
Pairs and lines
A locked pair or a box-line interaction removes candidates elsewhere. The pattern is useful only when it eliminates a real alternative, never as decoration.
- Keep notes exact
- Explain what is excluded
- Rescan for a new single
Advanced language
X-Wing is a constraint pattern, not a magic trick.
An X-Wing concerns the same candidate appearing in two positions across two rows and two matching positions in two columns. When the rectangle is genuinely locked, that candidate can be removed from other cells in those columns. It is a legitimate classic 9×9 technique, but it is rarely the best starting point for a newer player.
For an Evil Sudoku or late Killer Apex board, use advanced patterns slowly. Verify every cell in the pattern; if the proof cannot be described, return to simpler candidate work.
- ASingles first
Never overlook a direct placement while searching for a complex shape.
- BPairs second
Use pairs only when they restrict a third cell in the same unit.
- CPatterns last
Use an X-Wing or equivalent only when the two-by-two relationship is exact.
Practice route
Play the web sample →Technique is useful only when it helps the next move feel inevitable.
Try the browser board, then carry the same no-guess habit into the Android game’s continuous difficulty ladder when the official store editions are published.