Game objective
Fill the 9×9 grid so every row, column, and 3×3 box contains each digit once.
Controls
- Cell and number buttons: Select a blank cell and enter a digit
How scoring works
Completion time. A correct digit advances the solved grid The puzzle is completed or its countdown expires
Core mechanics
- A digit is valid only when it is absent from the selected cell's row, column, and three-by-three box.
- Given cells remain fixed while blank cells accept entries from the on-screen number controls.
- The countdown makes scanning order matter because repeated checks consume the same limited solving time as placements.
Common failure causes
- Checking only the row overlooks a duplicate already present in the column or local box.
- Guessing into a cell with multiple candidates creates contradictions that surface several moves later.
- Jumping between unrelated regions repeats candidate work and wastes the countdown.
How to recover a difficult position
After a contradiction or stalled region, return to the densest row, column, or box and list which digits are missing. Cross-check each missing digit against both intersecting units, place only a forced candidate, and then rescan the affected neighbors.
How we tested this game
Gameplay reviewed .
- Desktop
- Pointer entry was checked across fixed and blank cells, including legal digits, conflicting choices, countdown behavior, and reset.
- Mobile
- Touch emulation confirmed that cells and number controls remain selectable without horizontal overflow and that puzzle status stays visible.
Tips for Sudoku
- Start with rows or boxes containing the most given digits.
- Check both the row and column before placing a candidate.
- Use elimination instead of guessing when two cells look possible.
Frequently asked questions
What ends a run in Sudoku?
The puzzle is completed or its countdown expires
What should I focus on first in Sudoku?
Start with rows or boxes containing the most given digits.
Guides and collections
Developer and rights
- Owner, publisher, and operator
- Taopu Kuailema Trading Firm (Individual Industrial)
- Chinese legal name
- 天津市静海区桃浦快乐马商贸行（个体工商户）
- Registered operator
- HE TIANXIONG
- Brands
- Hersch Games / GameHersch
Sudoku is part of the curated MIT-licensed browser-game collection documented in the site rights and attribution record.
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