Fogbound Radio Duo - SOS Story
Guide a lost surveyor by radio
Only for iPhone
Expected Oct 23, 2026 · Free · In‑App Purchases
iPhone
"Can anyone hear me?" A lost surveyor's radio reaches only you. Guide her in real time with her grandfather's map and code. 5 endings, 8 bad endings, 6 secrets.
"This is Sawatari. Can anyone hear me? Over."
An earthquake has brought down a slope in Kirinosawa, a remote valley in Japan's Northern Alps. Haru Sawatari, a junior surveyor, is stranded on a ledge. Her senior is missing. Her phone has no signal. And somehow, her radio reaches only you.
Haru's messages arrive in real time. While she climbs, you really wait. At night, she sleeps too. You reply with two or three choices — and the reasons for the right answer are always somewhere in the story.
13 ENDINGS
Five endings and eight bad endings. Something you casually chose on the first night can catch up with you two nights later — the cause of every bad ending is planted earlier in the story, so it clicks in hindsight. After a lost signal you get a clue, and can jump back to your last choice or to the chapter where things went wrong.
SECRETS AND FORESHADOWING
The last pages of her grandfather's notebook are nothing but numbers. A thin line on his map with no name. "Six men," carved in a hut wall in 1974. An old voice you can only hear on one frequency. And on another run, Haru half-remembers you. Endings and secrets you find are kept in your Record.
RADIO WHEN CLOSED
Closed, your Duo's outer screen becomes a handheld radio. Haru's messages arrive as notifications, and you can answer from the notification buttons without opening it.
WHEN IN DOUBT, OPEN IT
Open your Duo: the notebook on the left side, the radio on the right. Her grandfather's 1974 map fills in with everything you learn. Tap Compare to put the 1974 valley on the left side and today's valley on the right, and you'll spot the lake that shouldn't be there and the trail that's gone.
A VOICE ON CHANNEL 4
Tune a faint voice out of the static by turning the dial that appears on screen.
WAITS THAT RESPECT YOU
- Choose Real time, Half or Instant waits, and change any time
- Nothing arrives during quiet hours (10:30 pm–7:30 am by default)
- At most 8 notifications a day
- Progress saves automatically
THE STORY
Six chapters. The English and Japanese were written side by side, scene by scene — not translated. Mountain-safety advice in the dialogue is limited to what we confirmed in public guidance from Japanese police and mountaineering bodies. (The story is fiction. In real mountains, file a plan and carry proper gear.)
ABOUT ADS
No ads during the story, on the closed outer screen, or in notifications — only under chapter-end cards and the chapter list. Remove ads with a one-time purchase. We'll never trade the next chapter for ad views or ratings.
OFFLINE & PRIVATE
The story, maps and sounds are all built in. Play to the end without a connection. Progress stays on your device. No account needed.
Designed around the iPhone Duo's fold — also playable on other iPhones.
Terms of Use: https://nayukitecture.com/works/duo-radio-terms-of-use.html
The developer, tasuku nayuki, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Used to Track You
The following data may be used to track you across apps and websites owned by other companies:
- Identifiers
- Usage Data
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Identifiers
- Usage Data
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- tasuku nayuki
- Size
- 5.1 MB
- Category
- Adventure
- Compatibility
Requires iOS 26.0 or later.
- iPhone
Requires iOS 26.0 or later. - Mac
Requires macOS 26.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 26.0 or later.
- iPhone
- Languages
- English and Japanese
- Age Rating
9+
- 9+
- Infrequent
Horror/Fear Themes
Contains
Advertising
- In-App Purchases
Yes
- Remove Ads $1.99
- Copyright
- © 2026 Tasuku Nayuki
