Put your phone down. Keep the light on.
Email kfashola@googlemail.com. Include your iPhone model and iOS version if you're reporting a problem.
Choose a length (8 hours by default) or an end time, then turn the phone face down or tap "Start without turning over". The app stores the start time and the planned end time. The watch continues while the phone is locked because it is based on the clock, not on the app staying open. At the planned end time the watch is complete; ending it sooner records it as ended early, with the time kept so far.
Does it block other apps? No. Lantern Keeper is a ritual and a timer. It does not use Screen Time features and cannot stop you opening other apps.
Does it track sleep? No. It measures time away from your phone and never claims to know whether you slept.
The face-down gesture isn't detected. Rest the phone screen-down on a flat surface for about a second. If your device can't report motion, the "Start without turning over" button does exactly the same thing.
The morning notification didn't arrive. Check Settings → Notifications → Lantern Keeper on your iPhone. The app only asks for permission the first time you switch "Morning notification" on, and a watch continues either way.
I opened the app during a watch. That's fine. The watch keeps running; "Return to watch" hides the controls again. Nothing is held against you.
Where's my data? On your iPhone only. There is no account and no cloud. See the privacy policy.
How do I delete history? Swipe an entry in the logbook, or Settings → "Delete all history". Both ask first and can't be undone.
Can I move data to a new phone? Lantern Keeper is included in your iPhone backup, so restoring a backup brings it across.
Lantern Keeper supports VoiceOver, Dynamic Type, Reduce Motion and Increased Contrast. The lighthouse is decorative; its state is always stated in text. If something doesn't work well with an assistive technology, please email; it will be fixed.