Sudoku
Generate and solve Sudoku puzzles.
About Sudoku
The GuruAlpha Sudoku game presents you with a classic 9x9 number puzzle where you must fill every row, column and 3x3 box with the digits 1-9 without repetition. The game generates unique puzzles at four difficulty levels, from beginner-friendly grids with many given numbers to expert puzzles that require advanced logic techniques. It is one of the most popular brain-training puzzles in the world.
Sudoku originated in Switzerland in 1783 and was popularized in Japan in 1984 before becoming a global phenomenon in the early 2000s. Unlike crossword puzzles, Sudoku requires no language knowledge — it is pure logic. This universality is part of its appeal: a Sudoku puzzle in a Japanese newspaper is identical to one in a British newspaper. The game has been shown to improve logical reasoning, concentration and pattern recognition.
The GuruAlpha implementation includes intelligent assistance features. The hint system highlights a cell where progress can be made, explaining the logic behind the suggestion. Error highlighting marks conflicting numbers in real-time, preventing you from building on mistakes. Auto-candidate mode fills in all possible numbers for empty cells, which is essential for solving harder puzzles that require elimination techniques.
Difficulty levels are determined by the number of given digits and the logic techniques required. Easy puzzles have 36-45 givens and can be solved by simple elimination. Medium has 30-35 givens and requires some advanced techniques. Hard has 25-29 givens and may require naked pairs or hidden singles. Expert has 22-24 givens and requires X-Wing, Swordfish and other advanced strategies.
The clean visual design features a clear grid with highlighted rows, columns and boxes as you select cells. The number pad at the bottom allows quick entry, and the note-taking mode lets you pencil in candidates. The timer and move counter track your solving speed, and statistics are saved locally to monitor your improvement over time.
Key Features of Sudoku
- Uniquely generated puzzles at four difficulty levels
- Intelligent hint system with logic explanations
- Real-time error highlighting
- Auto-candidate mode for advanced solving
- Note/pencil mode for candidate tracking
- Timer and move counter for speed tracking
- Statistics saved locally for progress monitoring
- Responsive design for all devices
How to Use Sudoku
- Open the Sudoku game on GuruAlpha.
- Select difficulty level (Easy, Medium, Hard, Expert).
- Tap an empty cell to select it.
- Enter a digit (1-9) using the number pad.
- Use note mode to pencil in candidate numbers.
- The hint button highlights where progress can be made.
- Fill the entire grid correctly to solve the puzzle.
Tips for Using Sudoku
- Start with Easy puzzles to learn basic elimination techniques.
- Scan rows, columns and boxes systematically for cells with only one possibility.
- Use note mode on hard puzzles to track candidate numbers.
- The hint system explains the logic — study the explanation to learn advanced techniques.
- Focus on rows/columns/boxes that are nearly complete for quick progress.
Frequently Asked Questions About Sudoku
Are puzzles generated uniquely?
Yes. Each puzzle is algorithmically generated to have exactly one solution. No two games are the same.
What makes Expert difficulty hard?
Expert puzzles have fewer given numbers and require advanced techniques like X-Wing, Naked Pairs, and Hidden Singles to solve.
Can I undo moves?
Yes. Tap the undo button or press Ctrl+Z to undo the last entry. You can undo multiple moves.
Is there a timer?
Yes. A timer tracks your solving speed. Your best times are saved for each difficulty level.