Diagonal Sudoku1 to 9 on the 2 diagonals too: free to play and print
Classic sudoku with one more rule. The 2 lines drawn corner to corner also hold 1 to 9 once each. No sign-up or app: play in your browser.
Who it's for Anyone used to classic sudoku who wants something a little different.
- LevelMedium, Hard, Oni
- Stages100 puzzles per level
- Free to playUnlimited at Medium
- Printable puzzles900 puzzles, with answers
Today's Diagonal Sudoku (Medium)11/13
Changes every day at 0:00 Japan time. Free to solve.
1Diagonal Sudoku rules
Every column, every row and every bold 3×3 box holds each digit 1 to 9 once. So far it is the same as classic sudoku.
On top of that, the 9 cells on each of the 2 diagonals, top-left to bottom-right and top-right to bottom-left, also hold 1 to 9 once each. The centre cell is on both 2.
How it differs from classic sudoku
- Rules
- Columns, rows and boxes, plus 1 to 9 once each on the 2 diagonals
- Cells
- 81 cells (the same 9×9 as classic)
- Clues
- Average of 25.8 at Medium (classic Medium averages 29.8)
- Level
- 3: Medium, Hard and Oni
2Level
Levels are set by the reasoning a puzzle needs. Every puzzle has one answer and has been checked to be solvable by logic alone, with no guessing.
| Levels and how to solve them | Clues | Browser | |
|---|---|---|---|
| MediumSolved just by finding where digits go. The diagonals help too | About 26 | Unlimited, free | 300 puzzles |
| HardWrite notes (candidates) and remove them with Pointing and pairs | About 24 | Chapters 1 to 3: 30 puzzles free | 300 puzzles |
| OniUses techniques that span the board, such as the X-Wing and XY-Wing | About 22 | Chapters 1 to 3: 30 puzzles free | 300 puzzles |
Stages come in 10 chapters of 10 puzzles at each level. Chapters 1 to 3 are free, and clearing 7 puzzles of a chapter opens the next. From chapter 4 on, each puzzle takes a ticket (none needed with the Lounge Pass).
3Medium stages, chapter 1
These are the first 10 puzzles of the game's stages for "Diagonal Sudoku, Medium". Chapter 1 is open from the start and free to play. Press a board to open that stage in your browser.
- 52948624953275947163965647Stage 1-126 cluesSolve →
- 91674131681873294921356963Stage 1-226 cluesSolve →
- 79245861361268371278349865Stage 1-326 cluesSolve →
- 85116838636993874948247598Stage 1-426 cluesSolve →
- 8895736239232648587642795Stage 1-525 cluesSolve →
- 56986872194796764982382673Stage 1-626 cluesSolve →
- 34914917146825337982583941Stage 1-726 cluesSolve →
- 58571328352956186491962178Stage 1-826 cluesSolve →
- 9647963478972628611287785Stage 1-925 cluesSolve →
- 64762858457175614157749253Stage 1-1026 cluesSolve →
4How to play
- Choose a kind In the game's "Play alone", choose Diagonal Sudoku under "Kind" at the top. The "Play alone" button at the top of this page has it selected from the start.
- Enter digits Select a cell and press a digit below. With "Notes" you can write small candidates.
- Stuck? Use a hint It does not show the answer straight away. It guides you in steps, starting with where to look.
For the basics of solving, with diagrams, see how to solve sudoku, with tips.
5Questions
What are the rules of Diagonal Sudoku?
As in classic sudoku, every column, row and 3×3 box holds 1 to 9 once each. On top of that, the 9 cells on each of the 2 diagonals, corner to corner, also hold 1 to 9 once each.
Is it the same as X-Sudoku?
Yes. Diagonal Sudoku and X-Sudoku are names for the same puzzle.
Is it harder than classic sudoku?
The extra rule means the diagonals give you more to go on. So fewer digits are given at the start: an average of 25.8 at Medium and 21.9 at Oni. Levels are set by the reasoning a puzzle needs, not by the number of clues.
Is it free to play?
In the browser, Random puzzles at Medium are free and unlimited. Hard and Oni take a ticket per puzzle (none needed with the Lounge Pass). Stages come in 10 chapters of 10 puzzles at each level, and the 30 puzzles of chapters 1 to 3 are free at every level.
Can I print them?
300 puzzles each at Medium, Hard and Oni are free to print. The answer is on page 2. The 2 diagonals are lightly tinted.
Are there hints?
Yes. Not the answer at once: you get where to look, the reasoning to use, the cell, then the digit. When a digit has only one place on a diagonal, that diagonal lights up.