X Sudoku 6×6 Easy — Set 99
Solver Notes
X-Sudoku on a 6x6 grid at Easy difficulty. The diagonal constraint adds a fresh layer to the compact 2x3 box format, solvable in 3-5 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 6x6 Grid
The 6x6 grid strikes a balance between accessibility and depth. With 36 cells in 2x3 boxes, puzzles take 3 to 10 minutes depending on difficulty. The 6x6 is large enough to showcase variant rules meaningfully — Killer cages have room to create genuine arithmetic puzzles, Windoku windows overlap in interesting ways — while remaining completable in a single sitting. Many players find the 6x6 their "daily driver" format: challenging enough to be satisfying, short enough to fit into a break.
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 (1-6 for 6x6)
- Use the constraint highlights to track which numbers are still available
- Print the puzzle if you prefer solving on paper