Objective: Fill the grid so that each column, each row, and each of the subgrids (the bold-lined boxes) contain all of the digits from 1 up to the board size, without repetition.
Rules:
- For a 9x9 board, use numbers 1-9.
- For a 6x6 board, use numbers 1-6.
- For a 4x4 board, use numbers 1-4.
- Each row must contain each number exactly once.
- Each column must contain each number exactly once.
- Each subgrid must contain each number exactly once.
Controls:
- Click on a cell in the grid to select it.
- Use the number palette at the bottom to place a number in the selected cell.
- New Puzzle: Starts a new game with the current settings.
- Check: Validates your current entries and highlights any incorrect numbers in red.
- Hint: Fills in one correct number in an empty cell for you.
- Erase: Clears the number from the selected cell.
- Undo/Redo: Step backward or forward through your moves.
- Settings: Change the board size, puzzle difficulty, and other visual options.