Sudoku on Board Gaming Hub is a full 9×9 grid with four difficulty presets — Easy, Medium, Hard, and Expert — plus pencil marks and undo. No account, no timer pressure unless you bring your own. This guide covers the techniques that take you from first fill to confident Expert grids.
The one rule
Each row, column, and 3×3 box must contain digits 1–9 exactly once. Every technique is just a consequence of that constraint plus the givens already on the board.
Level 1 — scanning
- Single candidate: If a cell can only be one digit, fill it immediately.
- Hidden singles: If a digit can only go in one cell within a row, column, or box, place it even when the cell has other pencil marks.
- Eliminate from givens: Before pencil marks, cross out digits already present in the cell’s row, column, and box.
Level 2 — pencil marks
Toggle pencil mode and note every possible digit per cell. Update marks after each placement — stale marks cause errors on Hard and Expert boards. On Easy and Medium, many puzzles solve with singles only if marks stay current.
Level 3 — pairs and triples
If two cells in a unit share the same two candidates and only those two, eliminate those digits from other cells in the unit (naked pair). The same logic extends to triples. This is the bridge technique between Medium and Hard.
Level 4 — X-Wing and beyond
An X-Wing appears when a digit’s candidates in two rows align in the same two columns (or vice versa), letting you remove that digit from other cells in those columns. Expert puzzles on the hub may require X-Wing, swordfish, or simple coloring — if stuck, step back and re-check for hidden singles after a fresh mark pass.
Choosing a difficulty
- Easy — singles only; good first week of play.
- Medium — occasional pairs; still relaxing.
- Hard — consistent mark discipline required.
- Expert — advanced eliminations; expect 30–45 minutes.