X Sudoku 9×9 Easy — Set 66
Solver Notes
Full-size X-Sudoku at Easy difficulty. The 9x9 grid gives the diagonal constraint room to shine — many cells can be deduced directly from the diagonal rule. 8-12 minutes.
X-Sudoku — Free Online & Printable
X-Sudoku adds a diagonal constraint to the classic sudoku rules. Both main diagonals — running from top-left to bottom-right and from top-right to bottom-left — must each contain the numbers 1 through 9 without repetition. This is the most accessible sudoku variant: the two extra constraints actually make many cells easier to deduce, since numbers on the diagonals are additionally restricted. If you''ve mastered standard sudoku and want a fresh twist without learning complex new rules, X-Sudoku (also called Diagonal Sudoku) is the ideal starting point.
About 9x9 Grid
The 9x9 grid is the full standard size for all sudoku variants. With 81 cells in 3x3 boxes, a 9x9 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 9x9 is where experienced solvers spend most of their time, and where the depth of each variant is fully revealed.
Easy Difficulty
Easy difficulty assumes you already know standard sudoku and are learning a new variant. Puzzles are 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/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 9x9, 30-90 seconds for 4x4.
How to Get Started
- Choose "New Puzzle" to generate a fresh puzzle with a unique solution
- Click or tap cells to enter numbers (1-9 for 9x9)
- Use the constraint highlights to track which numbers are still available
- Print the puzzle if you prefer solving on paper