🎯 Goal:

Fill the 9×9 grid so that each row, column, and 3×3 box contains the digits 1-9 without repeating.

🎮 Controls:

• Click a cell to select it (blue highlight)
• Click a number to fill the selected cell
• Note Mode: Add pencil marks for planning
• Clear: Remove a number from a cell
• Hint: Get the correct answer for an empty cell
• Undo/Redo: Go back or forward in history

⚠️ Rules:

• Each row must contain 1-9 (no duplicates)
• Each column must contain 1-9 (no duplicates)
• Each 3×3 box must contain 1-9 (no duplicates)
• Wrong numbers will turn red
• Correct placements will turn green