Classic Sudoku

📖 Overview

Classic Sudoku is a logic-based number placement puzzle. The objective is to fill a 9×9 grid with digits so that each column, each row, and each of the nine 3×3 subgrids contains all of the digits from 1 to 9. The puzzle starts with some cells already filled in, and your task is to complete the grid following the rules.

📏 Rules

• Fill every empty cell with a number from 1 to 9
• Each row must contain all numbers 1-9 without repetition
• Each column must contain all numbers 1-9 without repetition
• Each 3×3 box must contain all numbers 1-9 without repetition
• You can make up to 3 mistakes before the game ends
• The puzzle has only one valid solution

🎮 Controls

• Click Cell: Select a cell to fill
• Click Number: Enter number in selected cell
• Keyboard 1-9: Enter number directly
• Delete/Backspace: Erase cell content
• Notes Mode: Toggle to add small candidate numbers
• Undo: Reverse your last move
• Erase: Clear the selected cell
• Hint: Reveal one correct number
• Check: Verify your current solution

🏆 Scoring

• Complete the puzzle as quickly as possible
• Minimize mistakes (maximum 3 allowed)
• Harder difficulties provide greater challenge
• Use fewer hints for better performance
• Timer starts when you make your first move

💡 Tips

• Start with rows, columns, or boxes that have the most clues
• Use Notes mode to track possible candidates in each cell
• Look for naked singles (cells with only one candidate)
• Use hidden singles (numbers that can only go in one place)
• Scan rows and columns systematically for each number
• Practice regularly to improve pattern recognition
• Don't guess - every move should be logical

❓ FAQ