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A cube has six faces, and each face is a classic 9×9 sudoku: every row, column and 3×3 box must contain the digits 1 to 9 exactly once.

• Turn the cube by dragging with a finger or Apple Pencil. Let go and it settles on the nearest face. Pinch to zoom.
• Pick a cell by tapping it, then tap a digit on the number pad.
• Use Notes for pencil marks, Erase to clear a cell, and Undo / Redo freely.
• The little map of the cube shows how full each face is; tap a face there to jump to it.

New to it? The interactive tutorial on the home screen walks you through a nearly finished cube in a minute or two, and you can replay it anytime.

Where two faces meet, they're stitched together:

• Two cells that touch across a cube edge must hold different digits.
• The three cells that meet at a corner of the cube must all be different.

When you select a cell on the outer ring of a face, its neighbour on the next face is shown just past the edge, so you never have to guess what's around the corner. On the harder levels most faces can't be finished without using their seams. That's the fun part!

Easy needs only the basics (a digit that can only go in one place). Medium adds pairs and pointing candidates. Hard uses triples, X-Wings and similar patterns, often across seams. Ultra Hard asks for longer chains of reasoning. Every puzzle has exactly one solution and can be solved by logic alone; no guessing is ever needed.

Yes. Tap Hint and the app points to the next logical step and explains why it works. If you still want to, you can then reveal that digit. On Easy and Medium, mistake checking is on by default and marks wrong digits; on Hard and Ultra Hard you can turn it on in Settings.

Turn on Flat mode in Settings to solve one face at a time as a regular 2D grid, with an action to jump across any edge. Flat mode is also used automatically with VoiceOver, and every cell is described in full. Reduce Motion and larger text sizes are supported too.

Each of the four levels has 500 puzzles, and the first 20 in every level are free. A single one-time purchase of $0.99 (or the equivalent in your currency) unlocks every puzzle in every level. No subscription, no ads, no account.

Your purchase belongs to your Apple Account, so it comes with you for free:

1. Make sure you're signed in to the App Store with the same Apple Account you used to buy the unlock.
2. Open Sudoku Cubes and go to Settings ▸ Restore Purchases.
3. Approve the Apple sign-in prompt if one appears. Everything unlocks within a few seconds.

Usually you won't even need to do this, because the app checks your purchases automatically when it starts. If Family Sharing is turned on, members of your family group can unlock it the same way.

• Some purchases need approval (for example Ask to Buy). The app unlocks as soon as it's approved.
• Check your internet connection, then try Settings ▸ Restore Purchases.
• Check that in-app purchases are allowed in Settings ▸ Screen Time ▸ Content & Privacy Restrictions on your device.
• Refunds are handled by Apple at reportaproblem.apple.com.

Sudoku Cubes saves your progress on your device and keeps a small copy in your own iCloud account, so solved puzzles, best times and your current games show up on your iPhone and iPad. There's nothing to set up and no account to create; you just need to be signed in to iCloud with the same Apple Account on each device, with iCloud allowed for Sudoku Cubes.

Sync usually takes a few seconds but can take longer on a slow connection. If two devices have different progress, the app combines them: solved puzzles from both are kept, along with the best time for each.

• Check that both devices are signed in to iCloud with the same Apple Account (Settings ▸ [your name]).
• Make sure iCloud is turned on for Sudoku Cubes in Settings ▸ [your name] ▸ iCloud.
• Open the app on the device that has the progress, give it a moment online, then open it on the other device.

Without iCloud, progress stays safely on the device it was made on.

No. There are no analytics, ads or trackers, and no account. See our privacy policy for the details.