The game at a glance
Solve six mechanical puzzle boxes, uncover unsent letters and return for a shuffled daily challenge.
What changes on Duo?
Duo’s hinge acts as each box lid: closed shows the top, partly open reveals light, and flat opens the interior. Open flat first, then fold back to stand the lid as a mirror, lantern or lens.
A look inside
Developer App Store screenshots. These may show a standard iPhone or iPad layout; no Duo screenshot is confirmed for this listing.
How we chose this listing
This is a source-based listing. We have not tested this game on a physical iPhone Duo. Our latest catalog check is dated 2026-10-31. Read the supporting source ↗