Autosave — Your current game is saved in your browser after every move. If you leave the page, you'll be able to resume exactly where you left off. Saves are kept for 7 days.
Settings ⚙️ — For advanced players, the gear at the top of the page turns on the ✏️ Auto button: it fills in every candidate of the grid at once, or only the cleaned candidates (locked candidates removed). This second option counts as a hint: the game won’t count towards “No hints”. You’ll also find large print there, for easier reading.
Sudoku X stats — They are kept separate from your classic 9×9 sudoku stats. They're stored locally in your browser and never sent to a server.
Sudoku X: sudoku with diagonals
Sudoku X, also known as diagonal sudoku, takes the classic 9×9 grid and adds a single rule: the two long diagonals, from corner to corner, must also contain the numbers 1 to 9, with no repeats. The 17 cells involved are tinted gold on the grid.
That rule changes the way you play. A cell on a diagonal belongs to four groups at once (its row, its column, its box and its diagonal), and the center cell to five. Every number you place on a diagonal therefore tells you more than anywhere else, and the puzzles often start with fewer givens than a classic sudoku.
Sudoku-Land offers 3 levels (easy, medium, hard), notes mode, hints, autosave, a dark theme and the ⚙️ Settings menu. Every puzzle has a single solution and cannot be solved without the diagonals: each one has been checked individually.
Sudoku X rules
- Like a classic sudoku — every row, every column and every 3×3 box contains the numbers 1 to 9, once each.
- Plus both diagonals — each one also contains the numbers 1 to 9, once each.
- On the grid — when you select a cell on a diagonal, the whole diagonal lights up, just like its row, column and box.
Tips for solving a Sudoku X
- Start with the diagonals — count the numbers already on each one: few are usually missing, and a diagonal quickly gives a number away.
- Watch the center cell — it belongs to both diagonals, its row, its column and the middle box: it is the most constrained cell in the grid.
- Cross boxes and diagonals — a diagonal crosses the corner boxes and the center box on three cells. If, in one of those boxes, a number can only go on those three cells, it disappears from the rest of the diagonal (and vice versa).
- Let your notes clean themselves — with the “Clear related notes” option in the ⚙️ menu, a correct number is also removed from the notes along its diagonal.
All the grids on Sudoku-Land
Frequently asked questions
What is the difference between Sudoku X and classic sudoku?
Just one extra rule: both long diagonals must also contain the numbers 1 to 9, with no repeats. Rows, columns and boxes work exactly as in a classic 9×9 sudoku.
Is Sudoku X harder than classic sudoku?
Not necessarily. The diagonals add a constraint to respect, but they also give you more ways forward. At the same level, a Sudoku X mostly asks you to remember to look at the diagonals. Sudoku-Land levels are graded with the same techniques as classic sudoku.
Why is it also called diagonal sudoku?
It is the same game: the name Sudoku X comes from the X that the two diagonals draw across the grid. In French, it is called « sudoku diagonal » or simply Sudoku X.
Does the Hint button work like in classic sudoku?
Yes: the Hint button opens a step-by-step solver that takes the diagonals into account. It explains each deduction (a number with only one place left on a diagonal, a number confined to the diagonal within a box…) on a small grid with the diagonals tinted. Reading the steps is free; only “Apply this move” uses up a hint.