SleepTown
Keep a consistent sleep schedule and the app builds a town overnight.
SleepTown, from the creators of Forest, applies the same one-metaphor philosophy to sleep. You set a bedtime and wake-up goal; opening the app before your bedtime starts construction of a building, and waking up on schedule completes it. Keep a consistent sleep cycle and your buildings accumulate into a town.
The app later added a social element: building together with family and friends by hitting shared sleep goals, which adds gentle accountability to a habit that is otherwise invisible to others.
The design lesson: like Forest, SleepTown converts an abstract streak into a growing artifact you can look at. The town IS the streak, which makes breaking it feel like losing something real.
Read more on this
Longer write-ups covering this example and others like it:
