Jigsaw Sudoku 9×9 Hard — Set 78
Solver Notes
Jigsaw Sudoku replaces standard 3×3 boxes with irregularly shaped regions. Each region must still contain digits 1-9, but the jagged shapes create entirely different solving patterns every time.
What is Jigsaw Sudoku?
Jigsaw Sudoku (also called Irregular or Nonomino Sudoku) uses irregularly shaped regions instead of the standard 3×3 boxes. Each region contains exactly 9 cells and must hold digits 1-9 without repetition. The irregular shapes change which cells constrain each other, creating unique solving patterns that differ from every other puzzle.
How Region Shapes Affect Difficulty
Certain region shapes create "easier" puzzles because they naturally overlap with rows and columns in helpful ways. Other configurations create hard puzzles where you must carefully track which cells belong to the same region. Our generator uses a library of tested region templates to ensure clean, solvable puzzles at each difficulty level.
How do I identify which cells belong to which region in Jigsaw Sudoku?
Each region is shown with a distinct color or thick border. Cells sharing the same color or bordered together form one region that must contain digits 1-9 without repetition.