# On-Core Sudoku

> Classic Sudoku puzzle game with random generation and helpful tools. (iPhone/iPad app by On-Core Software LLC.)

- Source: https://appshunter.io/ios/app/on-core-sudoku/id287314682 (this page in markdown: same URL + `.md`)
- Developer: [On-Core Software LLC](https://appshunter.io/developer/283621364)
- Category: Games, Entertainment, Puzzle
- Price: $0.99
- Rating: 5.00/5 from 1 App Store ratings · 1 written reviews indexed
- Age rating: 4+
- Requires: iOS 9.0 · 11 MB
- Languages: American English
- Released: 2021-09-02
- Data updated: 2026-08-29
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/on-core-sudoku/id287314682/reviews.md

## What is On?

Challenge you brain!

On-Core Sudoku: consists of a nine-by-nine grid with 9 inner squares. To solve Sudoku each inner square must have one of the numbers between 1 and 9.  Each row and column must contain each number once. It features error checking, annotations (pencil marking), undo move(s) and more.

On-Core Sudoku features:
- Games are generated randomly so you will never play the same game twice.
- The game has three difficulty levels: Easy, Medium and Hard plus a Custom option for custom games.
- Each difficulty level has it's own timer so you can try to beat your best time at each level.
- The game auto-saves so that you can return to it at any time.
- Generate Symmetric or Non-Symmetric puzzles.
- Error checking to show invalid entered numbers.
- Annotate (pencil mark) a tile with one or more numbers.
- Unlimited Undo or Redo moves.
- Autofill option to automatically fill in all the possible annotations. 
- Option to enter custom games from sources such as newspapers, puzzle books, websites, etc.
- Wirelessly send or receive custom games, via a local WiFi connection, to a friend or family member who also has Game Pack Volume 1 or On-Core Sudoku.
- Sound effects can be turned on or off.
- No internet connection is required because the games are on your iPhone or iPod Touch.

## Key features

- Randomly generated puzzles
- Three difficulty levels plus custom
- Error checking
- Annotations (pencil marking)
- Undo/Redo moves
- Auto-save functionality
- Custom game input

## Recent user reviews (1 of 1)

All indexed reviews: https://appshunter.io/ios/app/on-core-sudoku/id287314682/reviews.md

### 1/5 — DO NOT BUY!!!!!!!!!

*2009-11-15*

1st yippe im the first!!
THIS GAME IS NO GOOD!!!!!!!!!!! NOT WORTH IT

## Frequently asked questions about On

### What makes On-Core Sudoku unique?

On-Core Sudoku features randomly generated puzzles, ensuring you never play the same game twice. It also offers a custom game input option, allowing you to enter puzzles from external sources.

### Can I play On-Core Sudoku offline?

Yes, On-Core Sudoku does not require an internet connection to play as the games are generated and stored on your device.

### Does On-Core Sudoku have ads?

No, On-Core Sudoku is ad-free, providing an uninterrupted puzzle-solving experience.

### What are the difficulty levels in On-Core Sudoku?

On-Core Sudoku offers three main difficulty levels: Easy, Medium, and Hard, along with a Custom option for personalized challenges.

### How does the error checking in On-Core Sudoku work?

The error checking feature highlights any invalid numbers you enter into the grid, helping you identify mistakes quickly.

### Can I share puzzles with friends using On-Core Sudoku?

Yes, you can wirelessly send or receive custom games to friends who also have On-Core Sudoku or Game Pack Volume 1 via a local WiFi connection.

### How often is On-Core Sudoku updated?

The app was last updated on October 29, 2024, indicating active development and support.

### What is the price of On-Core Sudoku?

On-Core Sudoku is available for a one-time purchase of $0.99.

## Version history (last 5 releases)

### 1.6 — 2024-10-29

Updated for latest iOS.

### 1.5 — 2021-09-02

Updated app and performance updates.

### 1.4 — 2014-11-22

This app has been updated by Apple to display the Apple Watch app icon.

Fixed issues for iOS 8.
Support for retina displays.

### 1.3 — 2010-05-26

iPhone OS 4.0 Compatibility

### 1.2 — 2009-06-25

iPhone OS 3.0 Compatibility

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## More apps by On-Core Software LLC

- [On-Core Wordfind](https://appshunter.io/ios/app/on-core-wordfind/id285884423)
- [PictureFlip](https://appshunter.io/ios/app/pictureflip/id285884811)
- [SalesCalc](https://appshunter.io/ios/app/salescalc/id286366281)
- [Wordfind Kids](https://appshunter.io/ios/app/wordfind-kids/id289277601)
- [Pachinko](https://appshunter.io/ios/app/pachinko/id303527165)

All apps by On-Core Software LLC: https://appshunter.io/developer/283621364

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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 2026-08-29.*