Windoku 9×9 Easy — Set 16
Solver Notes
Windoku — Free Online & Printable
Windoku, also known as Window Sudoku or NRC Sudoku, adds four fixed 3×3 window regions to the standard 9×9 grid. The windows are positioned symmetrically: top-left at rows 2-4, columns 2-4; top-right at rows 2-4, columns 6-8; bottom-left at rows 6-8, columns 2-4; bottom-right at rows 6-8, columns 6-8. Every window must contain digits 1-9 without repetition, in addition to standard row, column, and box constraints. The overlapping nature of windows and standard boxes creates rich constraint chains that experienced solvers find deeply satisfying.
About the 9×9 Grid
The 9×9 grid is the full standard size for all sudoku variants. With 81 cells in 3×3 boxes, a 9×9 variant puzzle takes 10 to 60+ minutes depending on difficulty level and variant type. All variant rules reach their full expressive potential at this size: Killer cages create complex arithmetic networks, Jigsaw regions form visually distinctive shapes, and diagonal constraints span the entire grid. The 9×9 is where experienced solvers spend most of their time, and where the depth and elegance of each variant rule is fully revealed.
Easy Difficulty
Easy difficulty is designed so that the variant's unique rule creates clear, immediate deductions. In X-Sudoku Easy, most diagonal cells can be filled using only the diagonal constraint plus row and column logic. Solving technique required: naked singles (cells with only one possible value) and direct constraint elimination. No candidate markup needed. Average time: 3-8 minutes for 9×9, 30-90 seconds for 4×4. If you are new to this variant type, Easy is where you build intuition for the extra rule before encountering combinations of constraints.
How to Get Started
- Choose "New Puzzle" to generate a fresh Windoku puzzle with a unique solution
- Click or tap cells to enter numbers (1–9)
- Use the constraint highlights to track which numbers are still available
- Print the puzzle if you prefer solving on paper