Questions, bugs or ideas? Email nbrgames.apps@gmail.com and include your iPhone model and the level number if it's about a puzzle. We usually reply within two days.
Open the game, go to Options → Restore Purchases. Use the same Apple Account you bought it with.
Every level has an ink target, shown by the mark on the ink bar. Solve it using that much ink or less for three stars. Any solve earns at least one.
Tap 💡 Hint to see where a line goes. After a few tries you can also skip the level and come back later.
On your iPhone. Deleting the app also deletes your progress.