Diabolical Sudoku: Hard Logic
No guessing. Pure logic.
Only for iPhone
Free · In‑App Purchases · Designed for iPhone. Not verified for macOS.
iPhone
No interrupting ads, ever. For players bored by ordinary sudoku, we serve up Demon-level difficulty. Stuck? Watch it solved, step by step.
Diabolical Sudoku is a no-nonsense sudoku app built for one thing: hard puzzles.
If easy sudoku has stopped being fun, this is for you—every puzzle is chosen to need real techniques like X-Wing, XY-Wing, and Swordfish.
■ Three difficulties
・Hard … solvable by logic alone, with real bite
・Expert … advanced techniques required
・Diabolical … X-Wing / XY-Wing / Swordfish-class stumpers
■ Highlights
・Step-by-step explanations … stuck on a puzzle? See which technique cracks which cell, one move at a time
・One unique solution … no guessing, ever. Pure logic always gets you there
・Controls your way … pick your input order (digit-first or cell-first) and your memo style
・Pencil marks, auto-candidates, highlighting, and reset
・Auto-save, with clear status and solve times recorded
・No interruptions … no full-screen ads breaking your concentration
One good puzzle at a time. Chase that "I solved it!" feeling, again and again.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
・You can now choose the size and darkness of the notes (candidates) in Settings.
・Four sizes and three darkness levels — set them to whatever is easiest for you to read.
The developer, kenta yamamoto, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Used to Track You
The following data may be used to track you across apps and websites owned by other companies:
- Usage Data
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Usage Data
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- kenta yamamoto
- Size
- 8.1 MB
- Category
- Puzzle
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
English and 18 more
- English, Dutch, French, German, Hindi, Indonesian, Italian, Japanese, Korean, Polish, Portuguese, Russian, Simplified Chinese, Spanish, Thai, Traditional Chinese, Turkish, Ukrainian, Vietnamese
- Age Rating
4+
- 4+
- Contains
Advertising
- In-App Purchases
Yes
- Remove Banner Ads $0.99
- Unlimited Candidates $3.99
- Unlock All Explanations $19.99
- 500 Explanation Tickets $9.99
- 80 Explanation Tickets $2.99
- 20 Explanation Tickets $0.99
- Copyright
- © 2026 kenta yamamoto.
