A variant keeps the 9×9 grid and the rules of classic sudoku (each digit from 1 to 9 exactly once per row, column and box), then adds just one more. That small extra rule is enough to change the way you reason. Both Sudoku-Land variants are free to play in your browser, with no sign-up, on computer or mobile.
Two variants to play online
Sudoku X, or diagonal sudoku
Both main diagonals, from corner to corner, must also contain the digits 1 to 9 with no repeats. On the grid, their 17 cells are tinted gold, and they light up when you select one of them.
The game starts with digits already placed, like classic sudoku, and needs no arithmetic. It is all about where you look: a cell on a diagonal belongs to four groups at once, and the center cell to five. Sudoku-Land’s grids cannot be finished without the diagonals, so you have to use them.
- Who it’s for: 9×9 players who want a change without learning to play all over again.
- The right reflex: count the digits already placed on each diagonal; often only a few are missing.
Full rules and more tips are on the game page: play Sudoku X.
Killer Sudoku, the sudoku of sums
The grid starts empty. It is divided into cages outlined with dots, and the small number in the corner of each cage gives the sum of its digits. A digit never repeats within a cage, and the usual row, column and box rules still apply.
Everything starts from the sums: two cells adding up to 3 must hold 1 and 2, three cells adding up to 24 must hold 7, 8 and 9. You don’t need to be good at math, simple additions are enough, and the page shows below the grid every possible combination for the selected cage. Each grid can be solved by logic alone, without ever guessing.
- Who it’s for: players who love numbers and long games, and 9×9 players looking for a real change.
- The right reflex: the rule of 45. A row, a column or a box always adds up to 45; take away the cages lying entirely inside it, and what is left is the sum of the other cells.
Full rules and more tips are on the game page: play Killer Sudoku.
Which variant should you choose?
Both variants have 3 levels, Easy, Medium and Hard, rated by the techniques needed to finish the grid. Start with Easy: a new rule always takes a little getting used to.
| At a glance | Sudoku X | Killer Sudoku |
|---|---|---|
| The extra rule | Both diagonals contain 1 to 9 | Each cage adds up to its sum, with no repeated digit |
| At the start | Some digits already placed | No digits, only the cages |
| Arithmetic | None | Simple additions |
| What helps | Tinted, highlighted diagonals | The cage’s combinations, below the grid |
| Who it’s for | Those who want familiar ground | Those who want something new |
In short: Sudoku X for a gentle first variant, Killer Sudoku for a truly different game.
The same tools as 9×9
The variants keep everything that makes classic sudoku comfortable on Sudoku-Land:
- 💡 A hint that explains. A window shows the next deduction in three steps (where to look, which technique, the answer), on a small grid with the diagonals or cages drawn in. Reading is free; only “Apply this move” uses up a hint.
- ✏️ Notes mode, and in the ⚙️ Settings menu, automatic notes that take the diagonals or the cage combinations into account.
- Automatic saving. Leave the page: your game waits for you for 7 days.
- Separate statistics for each variant, stored in your browser and never sent to a server.
- Reading comfort: dark theme, full screen and large print.
FAQ
What is a sudoku variant?
It is a sudoku that keeps the 9×9 grid and the basic rules (each digit once per row, column and box) and adds one constraint: the two diagonals for Sudoku X, the cage sums for Killer Sudoku. The grid is always solved by logic, with a single solution.
Which variant should I start with?
Sudoku X if you already play classic sudoku: it plays almost the same, you just need to keep the diagonals in mind. Killer Sudoku takes a little more getting used to, because the grid starts empty; start on Easy and use the combinations shown below the grid.
Do you need to be good at math for Killer Sudoku?
No. Simple additions are enough, and the same combinations keep coming back: two cells adding up to 3 are always 1 and 2. Sudoku-Land also shows below the grid the possible combinations for the selected cage.
Are the variants harder than classic sudoku?
Not necessarily. Each variant has 3 levels, from Easy to Hard, rated by the techniques needed to finish the grid. An extra rule adds a constraint to respect, but also new ways to move forward.
Are my classic sudoku statistics mixed with the variants’ statistics?
No. Sudoku X and Killer Sudoku each have their own statistics and their own save, stored in your browser and never sent to a server.
Ready to try?
One more rule, a whole new game.