Sudoku Classic

Classic Sudoku is a number-filling game that tests logical reasoning ability. Played on a 9×9 grid, the goal is to fill in numbers 1-9 in the blank spaces, satisfying specific rule constraints.

Basic Rules:

• Each row must contain numbers 1-9, without repetition
• Each column must contain numbers 1-9, without repetition
• Each 3×3 box must contain numbers 1-9, without repetition
• Some numbers are given at the start as solving clues

Controls:

• Click a blank cell, then click a number below to fill it
• Enable note mode to mark candidate numbers
• Error checking feature helps you verify if filled numbers are correct

Solving Techniques:

• Sole Candidate: A cell has only one possible number
• Elimination: Observe a row/column/box, eliminate present numbers to determine remaining positions
• Block Elimination: Use 3×3 box constraints to eliminate numbers in other areas
• Last Remaining: When a row/column/box has only one empty space, fill in the missing number

Difficulty Levels:

• Easy: Solvable with basic techniques
• Medium: Requires combining multiple techniques
• Hard: Requires advanced techniques like X-Wing, Swordfish, etc.
• Expert: Only for experienced Sudoku solvers

Tips:

• Start with cells that have the fewest candidate numbers
• Use notes to mark possibilities, avoid guessing
• Look for the same number appearing frequently in an area
• Solve easier areas first to unlock more clues