# Really Really Hard Sudoku — Classic & Killer to Nightmare

> Classic & Killer to Nightmare (iPhone/iPad app by Jeffrey Lipson.)

- Source: https://appshunter.io/ios/app/really-really-hard-sudoku/id6822091690 (this page in markdown: same URL + `.md`)
- Developer: [Jeffrey Lipson](https://appshunter.io/developer/6820863762)
- Category: Games, Board, Puzzle
- Price: Free
- Rating: 5.00/5 from 1 App Store ratings
- Age rating: 4+
- Requires: iOS 17.0 · 3 MB
- Languages: American English
- Released: 2026-10-29
- Data updated: 2026-11-01

## What is Really Really Hard Sudoku?

If the hardest puzzle in your daily paper is a warm-up, this is for you.

Every puzzle has exactly one solution and is solvable by logic — no guessing — and is graded by the hardest technique it actually needs. Seven tiers run from Easy to Nightmare in both Classic and Killer Sudoku.

HINTS THAT TEACH
• Hints get more specific one step at a time: the technique, then the digit, then where to look
• Lessons for every technique, with a worked example
• "Explain step by step": watch a chain or forcing argument unfold link by link, on an example or on your own board
• Mistake hints narrow down to the box, then the cell

PLAY YOUR WAY
• Normal and candidate entry, unlimited undo and redo
• Auto Pencil marks that remember the ones you cross out
• Killer cage helper and remaining sums (optional)
• Check and reveal when you need them — tracked in your stats, never forced on you

STATS
• Best and average times, streaks, clean solves, and the techniques you've beaten
• Share a solve when you finish a Nightmare

No accounts, no ads, no tracking. Works offline.

Plays on iPhone and iPad, with full hardware keyboard support.

## Is Really Really Hard Sudoku safe?

Not enough ratings yet to assess Really Really Hard Sudoku.

## Is Really Really Hard Sudoku legit?

Really Really Hard Sudoku has limited verification signals. The AppsHunter Legitimacy Score for Really Really Hard Sudoku is 58 out of 100 points across 7 verification signals from App Store and developer data.


## Version history (last 1 release)

### 1.0 — 2026-10-29

No release notes.

## More apps by Jeffrey Lipson

- [Just Between Us](https://appshunter.io/ios/app/just-between-us/id6820863760)

All apps by Jeffrey Lipson: https://appshunter.io/developer/6820863762

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-11-01.*