How can we help?
Answers to common questions are below. If you're stuck, found a bug or have an idea, get in touch. Every message is read.
To help us help you, include your device model (for example, iPhone Duo), your iOS version and the app version from Settings → General → iPhone Storage → Crease.
Playing
How do I enter numbers?
Tap a cell, then tap a number. Tap the same number again to clear it. With a hardware keyboard, use the arrow keys to move and 1–9 to enter.
How do pencil notes work?
Long-press any number to pencil it into the selected cell, or turn on Notes mode with the pencil button so every tap adds a note. When you place a digit, it's removed from the notes in the same row, column and box automatically. You can turn this off in Settings.
Why did a number turn red?
By default, Crease shows mistakes right away. If you'd rather find them yourself, open Settings and turn off "Show mistakes immediately". Then only digits that clash with another in the same row, column or box turn red.
How do hints work?
Tap Hint. If a cell is wrong, Crease points it out first. Otherwise it finds the next logical step, names the technique (like "Hidden single" or "X-Wing") and explains it. Tap the button on the hint to fill the cell in, or close it and try it yourself.
What do the difficulty levels mean?
Every puzzle has exactly one solution and is graded by the hardest technique it needs. Easy needs only singles; Medium adds pointing, box/line reduction and pairs; Hard adds triples and X-Wing; Expert adds Swordfish and XY-Wing; Master needs chains or forcing logic.
When does the daily challenge change?
At midnight in your time zone. Everyone gets the same puzzle each day. It's gentlest on Mondays and toughest at the weekend. Solving it on consecutive days builds your streak.
iPhone Duo
What happens when I unfold my phone mid-game?
Nothing is lost. The board moves to the left of the crease, the keypad and stats move to the right, and your selection, notes and timer carry over.
How do I use the half-folded (tabletop) layout?
Turn the open phone sideways so the crease is horizontal, then half-fold it and set it down. The board sits on the upper half and the keypad on the lower half. The same layout appears on iPad in portrait.
Does Crease work on other iPhones and iPad?
Yes. Crease runs on any iPhone or iPad with iOS 18 or later and adapts its layout to the screen.
Your data
Where is my progress saved?
On your device. Your current game, stats and settings are saved automatically as you play. Crease has no accounts and doesn't sync, so deleting the app also deletes your progress.
Does Crease collect any data?
No. Crease works fully offline and collects nothing. See the privacy policy for details.