Game Rules & Features

Core Rules

Complete the 9×9 grid so every row, column, and 3×3 box contains the digits 1 through 9 exactly once.

Game Mechanics

• Correction Lock: An incorrect number stays red. Correct it or use Erase before filling another cell.
• Heart System: You begin with three hearts. A new incorrect attempt removes one heart. Repeating the same wrong number in the same cell does not remove another heart, and play continues after all hearts are gone.
• Two-Choice Hints: Select an empty cell and press Hint to receive two numbers to consider. Choosing one uses a hint. Opening or cancelling the hint does not. Each puzzle includes two hints.

Desktop Controls

• Arrow keys: Move between cells.
• Number keys 1–9: Enter a digit.
• Backspace or Delete: Clear the selected cell.
• Space: Save the game and open a separate digital clock page. The game timer pauses while you are away.
• Shift twice: Return from the clock to the saved game.