Oni Sudoku Oni puzzles, free to print
Very hard Oni sudoku that goes as far as the X-Wing and XY-Wing. Free to print, with answers, and 30 stages are free in the browser with no sign-up.
Who it's for Anyone who can solve Hard and wants to take on advanced techniques such as the X-Wing and Swordfish.
- Typical time1 hr or more
- CluesAverage of 28
- Printable puzzles500 puzzles
- Free to play30 stages
今日の超上級の問題を解く →超上級の印刷用 500 問（答えつき）
- Print All 500 free, with answers
- Browser 30 stages free
- Other puzzles A ticket per puzzle (none needed with the Lounge Pass)
Today's Oni puzzle11/13
Changes every day at 0:00 Japan time.
1The key to Oni is the X-Wing
In Oni, looking inside one column or row will no longer get you anywhere. Compare where a digit can go across the whole board.
In the figure above, 5 can go only in the 2 places in columns 3 and 8, in both row 2 and row 6. In either row, 5 goes in one of these 2 columns, so 5 cannot go in the other cells (×) of columns 3 and 8.
Tips for Oni
- To find an X-Wing, pick a digit and list the rows where it can go in only 2 places. If 2 rows line up in the same 2 columns, that is the pattern.
- If a cell with only A and B as candidates sees a cell with A and C and a cell with B and C, that is an XY-Wing. C can be removed from any cell that sees both of those 2 cells.
- When you cannot find a technique, go through the digits from 1 to 9 and compare the layout of candidates across the whole board.
Techniques for Oni
Guides with examples
2How the levels differ
Levels are set not by how many digits are given at the start, but by the reasoning a puzzle needs.
| Levels and key techniques | Typical time | Clues |
|---|---|---|
| EasyJust find the missing digits | 5 to 20 min | 38 |
| MediumWrite notes (candidates) and narrow down | 15 to 30 min | 30 |
| HardRemove candidates with pairs | 30 min to 1 hr | 27 |
| OniPatterns that span the board, such as the X-Wing | 1 hr or more | 28 |
Hard and Oni start with about the same number of clues (averages of 27.2 and 27.6). Even with many digits, you cannot get far in Oni without finding patterns that span the board, such as the X-Wing.
The game has one more level above Oni, called Master, making 5 levels in all. Master can only be played in the game.
3Oni stages, chapter 1
These are the first 10 puzzles of the game's Oni stages. Chapter 1 is open from the start and free to play. Press a board to open that stage in your browser; the stars you earn stay on the stage.
- 5196428832619329467685799541Stage 1-128 cluesSolve →
- 8763411238712652613971934637Stage 1-228 cluesSolve →
- 16897275785156934213658278Stage 1-326 cluesSolve →
- 7156528512459826723172686491Stage 1-428 cluesSolve →
- 672434182925765727615786515132Stage 1-530 cluesSolve →
- 9817328956239536179248937682Stage 1-628 cluesSolve →
- 517415617245784353194361854662Stage 1-730 cluesSolve →
- 57233576213498146878281625Stage 1-826 cluesSolve →
- 63251891756385687494265531Stage 1-926 cluesSolve →
- 5174975643583821575629135473Stage 1-1028 cluesSolve →
4How to play
- Open a puzzle Press "Solve today's Oni puzzle" and the board opens in your browser. No app or sign-up needed. In the browser, Oni takes a ticket per puzzle (none needed with the Lounge Pass).
- 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 rules and how to solve, with diagrams, see how to solve sudoku, with tips.
5Questions
What techniques does Oni use?
The X-Wing, the Swordfish, the XY-Wing and others. Each has a guide page with an example.
Can I play Oni puzzles for free?
In the browser, these are free: the 10 puzzles of stage chapter 1 on this page, everything up to chapter 3 (30 puzzles), and the Daily puzzle, whose level changes by day of the week. Chapters from 2 on open when you clear 7 puzzles of the chapter before. Other Oni puzzles take a ticket per puzzle, and the Lounge Pass lets you play as many as you like. All 500 printable puzzles are free and come with answers.
Do I need to guess (trial and error)?
No. Even the hardest puzzles have been checked to be solvable by logic alone, without trial and error or proof by contradiction.
Why are there more clues than in Hard?
A sudoku's difficulty depends less on how many digits are given at the start than on the techniques needed to solve it. Oni may have more digits, but you cannot get far without finding patterns such as the X-Wing.
Are there harder puzzles?
There is an even higher level, Master. It needs techniques one step further, such as the Skyscraper and the XYZ-Wing.