Sudoku

How to play

1. 1Choose easy, medium, or hard.
2. 2Fill each empty cell with a number from 1 to 9.
3. 3Keep every row, column, and 3 by 3 box unique.
4. 4Use the number pad, hint button, and mistake toggle as needed.

Rules

• Every row must contain each number from 1 to 9 once.
• Every column must contain each number from 1 to 9 once.
• Every 3 by 3 box must contain each number from 1 to 9 once.
• Starting clues cannot be changed.

Scoring

• Sudoku is complete when the full grid matches the valid solution.
• The timer tracks each solve locally.
• Best times are stored by difficulty.
• After completing a puzzle, start another Sudoku puzzle without waiting.

Tips and strategy

• Begin with rows, columns, or boxes that already have many clues.
• Look for cells where only one number can fit.
• Use the mistake toggle while learning, then turn it off for a paper-style challenge.
• Take a hint only after checking the related row, column, and box yourself.

Difficulty explanation

Easy

More starting numbers and a gentler solve path for warmups.

Medium

Fewer clues, with more scanning across rows, columns, and boxes.

Hard

The lightest clue set, best for slower solves and careful notes.

Beginner tips

• Start with rows, columns, or boxes that already have many numbers.
• Look for a number that can only fit in one cell within a 3 by 3 box.
• Use the mistake toggle when learning, then turn it off for a calmer paper-style challenge.
• If stuck, take one hint and study why that number fits before continuing.