User guide

In brief

Sudoku Unbound is a Sudoku game for iPhone and iPad. You fill a grid with digits following one simple rule, and the app helps you with notes and hints that explain the logic instead of giving away the answer. Classic 9×9 has five levels; Mini 6×6 is for a short game.

It is for anyone who likes logic puzzles, from complete beginners to experienced players. Recommended path: read the rule (1 minute), play your first game at Easy (10 minutes), then learn notes and hints (5 minutes).

1. Before you start

• An iPhone or iPad with iOS 26 or iPadOS 26 or later.
• No account and no internet connection are needed to play. The connection is used only to buy or restore Pro, for iCloud sync, for Game Center and, if you leave it on, for the update check.
• The app is available in Italian, English, Spanish, German and French and follows your device language.

What the app does not do: it never asks you to create an account, has no rankings except the optional Game Center leaderboards, never limits your mistakes and shows no ads. Your Apple Account is enough to take your progress to a new iPhone or iPad (see Move to a new iPhone or iPad).

2. Download and first launch

1. Open the App Store, search for Sudoku Unbound and download it (once it is available).
2. Open the app.
   What you'll see

   The Home screen with a Welcome card, the Mini 6×6 and Daily Challenge cards, Your path with the five levels, and the New 9×9 game button at the bottom.

3. To read the rules inside the app, tap How to play on the Welcome card.

The app asks for no permissions and needs no sign-in. Next: the rule.

3. The rule

Fill every row, column and box with each digit exactly once. 9×9 uses digits 1 to 9 and boxes of 3×3; Mini uses 1 to 6 and boxes of 2×3. Every puzzle has one solution and can be solved by logic alone.

The digits already in the grid when you start are the givens: you cannot change them.

4. Play your first game

1. On Home, tap New 9×9 game.
   What you'll see

   The Choose the level panel with five levels. Hard, Expert and Extreme show a lock: they are part of Pro.

2. Tap Easy.
   What you'll see

   The grid, with the timer above it, the buttons Undo, Redo, Erase, Notes and Hint, and the number pad below. Under each digit the pad shows how many are left to place.

3. Tap an empty cell. Its row, column and box are highlighted.
4. Tap a digit on the number pad to write it in the cell.
5. To remove a digit, tap the same digit again, or tap Erase.
6. Made a wrong move? Tap Undo. Redo brings it back. Both work without limits.

If a digit is already in the same row, column or box, the grid marks the conflict and shows how many conflicts there are. When you complete a row, column or box, it lights up briefly. When the grid is solved, you see Solved. with your time.

For a quicker game, tap the Mini 6×6 card on Home and choose Easy or Medium.

Leave and come back

Go back to Home whenever you want: the game is saved automatically. On Home, the Game in progress card shows the level, time and filled cells; tap Continue.

Next: use notes.

5. Use notes

Notes are small digits you pencil into a cell to remember which digits could still go there (candidates).

1. Tap Notes. The button now reads Notes: on.
2. Tap a cell, then tap one or more digits. They appear small inside the cell.
3. Tap a note digit again to remove it.
4. Tap Notes: on again to go back to writing normal digits.

To fill every empty cell with all its possible candidates at once, tap More (the button at the top right of the game) › Fill in all notes. You can undo it with Undo.

Check your notes

Not sure your notes are right? Tap More › Check my notes. If every note includes the right digit, you see Your notes all include the right digit. Otherwise the app tells you how many cells have notes without the right digit and marks them. It does not place or reveal any digit.

Color marks

To keep track of an idea, put a color mark on a cell: select the cell, tap More › Color mark and choose Green circle, Violet square, Terracotta diamond or Slate hexagon. Each mark also has its own shape, so you can tell them apart without relying on color. No mark removes it.

6. Ask for a hint

A hint does not just give you the answer. It works in three steps, and you decide how far to go. Hints use only logic, never guesses, and they are free and unlimited.

1. Tap Hint.
   What you'll see

   Step 1 of 3: the name of the technique to use and where to look (for example “Look here: Row 4.”). Try to find the move yourself, or continue.

2. Tap Explain.
   What you'll see

   Step 2 of 3: a short explanation of why the technique works in that spot.

3. Tap Place the … (with the digit) to let the app place it, or tap I'll find it to close the hint and do it yourself. You can undo a placed hint with Undo.

Two special cases:

• Fix this first: some of your digits do not lead to the solution. They are highlighted; tap Clear to remove them and continue.
• Reveal a cell: from that point none of the techniques this app teaches gives a next step. Tap Reveal to show one cell. This is not a deduction.

Hints you use are counted in the game and in your statistics (Without hints counts the games you solved without any).

7. Levels and techniques

Each level is defined by the hardest technique the puzzle needs, not by the number of clues. A puzzle at one level cannot be solved with only the techniques of the levels below.

• Easy (Singles only): Last empty cell, Naked single, Hidden single.
• Medium (Pairs and box–line interactions): Pointing, Box–line reduction, Naked pair, Hidden pair.
• Hard (Triples and X-Wing): Naked triple, Hidden triple, X-Wing.
• Expert (Swordfish, XY-Wing and XYZ-Wing): Swordfish, XY-Wing, XYZ-Wing. The Techniques guide also explains Naked quad and Hidden quad, which no puzzle in the app needs yet.
• Extreme (Coloring and chains): Simple coloring, W-Wing, X-Chain, XY-Chain.

Mini 6×6 has Easy (Quick, singles only) and Medium (Quick, with pairs).

Easy and Medium are free; Hard, Expert and Extreme are part of Pro. The hint for each move tells you the technique by name, so you learn them as you play.

8. Play the Daily Challenge

Every day there is one new Classic 9×9 grid at Medium level. It is free.

1. On Home, tap the Daily Challenge card. It shows the challenge number and Today's grid · Medium.
2. Solve it like any other game. You can leave and come back: the card then shows In progress.

The day follows your device's date and time zone. The Daily Challenge has its own save, so it never replaces your regular game.

Daily archive

To play a day you missed, tap the calendar button on the Daily Challenge card, or touch and hold the card and choose Daily archive. Each day shows its number: solved days are filled in with your time, a pencil marks a day in progress. Tap a day you have not solved to play it. If an unfinished Daily from another day is saved, the app first asks Switch Daily?; Play this day replaces that unfinished Daily.

9. Check your statistics

1. On Home, tap the chart button at the top right (Statistics).
2. Scroll through Classic 9×9, Mini 6×6 and the Daily Challenge.

For each level you see Solved, Started, Best and Average time and Without hints. Before your first solved grid you see No games yet.

At the end of every game the result screen shows Time, Best time (with New best when you beat it), Hints, Corrections and Solved at this level. Statistics are saved on your device; with Sync with iCloud on, the statistics of all your devices signed in with the same Apple Account are added together and shown on each of them.

Game Center: leaderboards and achievements

Game Center is Apple's game service, and it is optional. With Game Center on in the settings (it is on at start), Apple may ask you to sign in when the app opens. Once you are signed in, a controller button appears at the top right of Home (called Game Center for VoiceOver) and opens the Game Center dashboard with the leaderboards and achievements.

• Time leaderboards: one for each level of Classic 9×9 and for Mini 6×6 Easy and Medium, plus one for the Daily Challenge. Only today's Daily Challenge is ranked, not a day played from the archive, and the Daily board starts a new day at midnight UTC.
• Puzzles solved: a leaderboard with the total number of grids you solved on all your devices.
• 18 achievements: milestones such as your first grid, each level, 10 to 500 solved grids, 10 to 100 Daily Challenges or a grid solved without hints. There are no streaks and no time pressure.

Only a grid solved without any help reaches a time leaderboard: no hint, no revealed cell, no Check my notes and no live mistake marking (Show mistakes). When you finish a ranked game, the result screen shows a Leaderboard button; if you used help, it says that this time stays off the leaderboard. The number of solved grids always counts.

Apple handles sign-in, scores and achievements under its own privacy policy, and nothing reaches us (see the privacy policy).

10. All settings

Open them from Home with the gear button at the top right, or in a game from More › Settings. Changes apply immediately. Tap Done to close.

• Appearance (System, Light, Dark). Starts on System: the app follows your device.
• Show timer. On at start. Turn it off to play without seeing the time; the time is still recorded for your statistics.
• Clean notes automatically. On at start. When you place a digit, it is removed from the notes in the same row, column and box.
• Highlight row, column and box. On at start. Highlights the area around the selected cell.
• Highlight the same digit. On at start. Highlights every cell with the digit you selected.
• Larger notes. Off at start. Draws the notes in the cells bigger, so they are easier to read.
• Keep the screen on while playing. On at start. The screen does not dim or lock while a game is running; when you pause or finish, your device's normal Auto-Lock applies again.
• Sounds and Haptics (section Sound and haptics). Both on at start. Sounds follow the silent switch and never stop your music.
• Number first (section Input). Off at start. Tap a digit first, then the cells where it goes.
• Keypad on the left (section Input). Off at start. On wide screens like iPad, the buttons and number pad move to the left of the grid.
• Sync with iCloud (section iCloud and new devices). On at start when you are signed in to iCloud. Keeps your settings, statistics, Daily Challenge history, the puzzles you have already played, your game in progress and your Daily Challenge in progress in your own iCloud, so your devices stay in step and a new iPhone or iPad picks up where you left off (see Move to a new iPhone or iPad). The iCloud row below shows Connected. If the device is not signed in to iCloud, the section shows Not signed in on this device: your progress stays only here.
• Delete my data from iCloud (same section). After you confirm with Delete from iCloud, it removes everything the app keeps in your iCloud, for all your devices. What is on this device stays. See Delete your data and the app.
• Game Center. On at start. Lets the app use Apple's Game Center for leaderboards and achievements; see Game Center: leaderboards and achievements. Turn it off and the app does not use Game Center.
• Show mistakes. Off at start. Marks digits that do not match the solution. There is never a limit on mistakes. You can also switch it in a game from More.
• Pro: Unlock Pro or Pro is active on this Apple Account, and Restore purchases.
• Tell me about updates. On at start. No more than about once a day, when you open the app, it asks the App Store whether a newer version exists and, if so, shows the Update available notice on Home; Update opens the App Store. Closing the notice hides it for that version. Turn it off and the app makes no update check. The game is never blocked.
• Help: How to play and Techniques open inside the app; User guide, Support and Privacy open this website.

At the bottom you find the app Version, useful when you write to support.

11. Pro and purchases

Pro unlocks Classic 9×9 at Hard, Expert and Extreme. It is one purchase, forever, with no subscription. Hints, notes and statistics stay free, and there are no ads for anyone.

1. Tap a locked level, or open Settings › Unlock Pro.
   What you'll see

   The Sudoku Unbound Pro screen with what Pro includes and the price, shown by the App Store in your currency.

2. Tap Unlock Pro (the button shows the price) and confirm with your Apple Account.
   Attention

   This is a real payment through your Apple Account. Check the price before you confirm.

3. When the purchase is complete you see Pro is unlocked. Thank you. and the levels open.

• Waiting for approval: the purchase needs approval (for example Ask to Buy). Pro unlocks by itself once it is approved.
• On another device with the same Apple Account, Pro usually appears on its own. If not, tap Restore purchases.
• Refunds are handled by Apple. After a refund the Pro levels lock again; saved progress is kept.

12. Accessibility

The app is built to work with the accessibility settings of iOS and iPadOS. VoiceOver compatibility on a physical device has not yet been verified.

• VoiceOver: each cell announces its row and column, its digit (given or entered by you) or its notes. Double-tap to select a cell, then use the number pad. Erasing is also available as a VoiceOver action on the cell. Conflicts, completed rows, columns and boxes and the solved grid are announced.
• Larger text (Dynamic Type): text and buttons grow with your text size setting; layouts rearrange at the largest sizes.
• Reduce Motion: animations are reduced when this is on.
• Increase Contrast and Reduce Transparency: backgrounds become solid and contrast increases.
• Light and dark: choose in Appearance or follow the system.
• Sounds and Haptics can each be turned off in Settings.

13. iPad and wide screens

The layout follows the space available, not the device model:

• In a tall space (iPhone held upright, iPad in portrait) the grid is at the top and the buttons and number pad are below it.
• In a wide space (iPad in landscape, a wide window) the grid is on the left and the buttons and number pad are in a column on the right.

The app works in every orientation. On iPad it adapts when you resize its window. Your game continues when the layout changes.

14. Widget, Siri and Shortcuts

The Daily Challenge widget shows today's challenge on the Home Screen or the Lock Screen. Add it like any other widget: touch and hold an empty area of the Home Screen or the Lock Screen, choose to edit or customise it, add a widget and pick Sudoku Unbound. Tap the widget to open the Daily Challenge.

With Siri or the Shortcuts app you can use two actions: “Start today's Daily” opens today's Daily Challenge, and “Resume game” continues your saved game.

To keep the widget up to date, the app writes today's Daily Challenge status (date, number, state and time) to a storage area on your device shared only with its own widget. The widget and the actions make no internet connection and send nothing.

15. If something goes wrong

The Daily Challenge card says “Not available”.

Why: the app could not find today's grid in its puzzles. What to do: update the app from the App Store; if it continues, write to support.

Home shows “The puzzles could not be loaded”.

Why: the app's puzzle files are damaged. What to do: delete and reinstall the app. Note that this also deletes the games and statistics saved on this device; with Sync with iCloud on, they come back from your iCloud when you open the app again.

Home shows “A saved game could not be read”.

Why: a save file was damaged. The app set it aside safely and your statistics are kept. What to do: tap Close and start a new game.

“This game needs Pro”.

Why: the saved game is at a Pro level and Pro is not active on this device. What to do: Restore purchases or unlock Pro. Your progress is saved.

“The App Store is not reachable right now”.

Why: no connection to the App Store. What to do: check your connection and try again later. Everything free keeps working.

A notice on Home says a new version is available.

Why: the App Store has a newer version for your device. What to do: tap the notice to open the App Store and update, or close it and keep playing. To stop these notices, turn off Tell me about updates in Settings.

I hear no sounds.

Why: Sounds is off, or the silent switch is on. What to do: check Settings › Sound and haptics and the silent switch.

Still stuck? Write to info@ifgecommerce.com with your device model, system version, app Version and what happened. More answers on the Support page.

16. Move to a new iPhone or iPad

There is no account to create. Your Apple Account is enough: with Sync with iCloud on, the app keeps your progress in your own iCloud, and it comes back on any iPhone or iPad signed in with the same Apple Account. Nothing goes to our servers.

1. On your old device, check that Sync with iCloud is on (Settings › iCloud and new devices) and open the app once while you are online, so your latest progress reaches iCloud.
2. On the new device, sign in with the same Apple Account and install Sudoku Unbound.
3. Open the app. Your settings, statistics, Daily Challenge history, the puzzles you have already played, your game in progress and your Daily Challenge in progress come back by themselves. The first time, this can take a moment.
4. Pro comes back from the App Store on its own. If it does not, tap Settings › Restore purchases.

If another of your devices has a different game in progress, Home shows Game from your other device. Tap Continue here to play it on this device (it replaces the game saved here), or close the notice to keep your own game. A game you are playing is never swapped.

A game travels with up to its last 100 moves to undo; Redo starts empty on the other device. If you set up the new device from an iCloud Backup or by transferring data from your old iPhone, the app recognises the copied data and does not count your statistics twice.

17. Delete your data and the app

The app keeps your data in two places: on your device and, with Sync with iCloud on, in your own iCloud. There is no button that resets your statistics on the device.

Delete what is in your iCloud

1. Open Settings › iCloud and new devices and tap Delete my data from iCloud. The button appears when the device is signed in to iCloud.
2. Confirm with Delete from iCloud. You see Deleted from iCloud. Turn sync off too if you don't want it to start again.
3. Turn off Sync with iCloud on this device, and on your other devices, if you do not want them to save to iCloud again.

This removes the settings, statistics, Daily Challenge history, played-puzzle memory and games in progress that the app keeps in your iCloud, for all your devices. What is on this device stays. Turning sync off on its own does not delete what is already in iCloud.

Delete what is on the device

1. On the Home Screen of your device, touch and hold the Sudoku Unbound icon.
2. Tap Remove App, then Delete App.

Pro stays linked to your Apple Account: after reinstalling, tap Restore purchases. Read the Privacy Policy for details.

18. Glossary

• Cell: one square of the grid.
• Row, column: a horizontal or vertical line of cells.
• Box: one of the outlined blocks (3×3 in Classic, 2×3 in Mini).
• Given: a digit already in the grid at the start; it cannot be changed.
• Candidate: a digit that could still go in a cell. You write candidates with notes.
• Conflict: the same digit twice in one row, column or box.
• Technique: a named logical reasoning that places a digit or removes candidates.
• Pro: the optional one-time purchase that unlocks Hard, Expert and Extreme.