The Hidden Ending and the Twelve Echoes
Version: the 25 October 2026 rewrite. The old "journalist / ancient leviathan / three endings" version is gone; it is now "finish your missing brother's five letters," with four endings. Spoilers: the ending choice, the hidden 34.2, the twelve echoes and the fourth choice. Where these numbers come from: everything below — the four questions, four endings and twelve echoes — is what the 25 October 2026 rewrite actually contains, not an estimate. You see them in the game like this: the four questions are the prompt boxes in the four recipients' conversations; the four endings are on the final choice screen; the twelve echoes are in the Echoes codex (bottom-left button, shows n/12). Chinese and English lines match one to one.
A correction to the old guide
The old guide said "5 regions, 5 deliveries, 4 puzzles, 3 endings, and there is no Act 8 with eight hidden clues." The second half was right: there is no "Act 8" and no eight hidden clues — that label was just carried over from the old naming; the game has no chapter numbering at all. But the game has had four endings since 19 October 2026:
- Publish the five letters
- Give them to the families and seal the station
- Put the fifth letter back into the pump (hidden entrance)
- Twelve echoes + the fifth letter (only after all echoes)
The 25 October rewrite changed their content and motive, not their number.
Where 34.2 comes from
Dr. K gives two numbers in the lab:
- pump station: 52.9 hertz
- beneath Lan City: 18.7 hertz
What the outside hears is neither, but their difference:
52.9 − 18.7 = 34.2
Below the ending choices is an input asking for "the figure you worked out (hertz)." Enter 34.2 to reach the hidden ending; 52.9, 18.7, 34.3 and 18.98 are all refused.
It cannot be copied: 52.9 shows up several times in the game — Su Qing says it, Ming Yue says it, Dr. K says it, and his EEG records it at minute seven. 18.7 appears only once, in the line where Dr. K hands you those two numbers. But 34.2 appears in no dialogue, file or echo at all; Dr. K even says he won't write that number into any letter. The subtraction is yours.
What the hidden ending does
You open the fifth letter. Inside isn't paper but a short length of audio tape. You patch it into the pump console and play it at the 34.2 difference. Three seconds later the whole island goes quiet—even the waves stop. Then the console answers with your brother's voice:
"I locked the door myself. Don't wait for me."
The recording ends; the pump resumes, four seconds a beat. He doesn't come back, but you know he wasn't left in the dark. He stayed where he chose to stay.
This ending doesn't change whether he is alive. It changes how you understand his choice.
Where the twelve echoes are
Echoes don't change the main branch; walk close to a glimmer to collect them. All twelve add the fourth button to the ending screen. In the Echoes codex they're sorted by region, and each has its own picture.
- Lighthouse & Dock: The Six-Second Lead, The Scorched Nameplate.
- Southern Coral Reef: Lin Yu's Route Book, The Fish That Stayed.
- The Wreck: The Back of the Chronicle, The Later Coin.
- Bone Shrine: The Thirteenth Rib, The Caretaker Roll.
- Abyssal Lab: Minute Seven on the EEG, Coral of Two Ages.
- Two more (out on the sea lanes): The 1978 Hand-Drawn Sonar, To the Next Courier. These two aren't in the five districts; they sit between regions and are picked up as you travel, falling under the "Region" group in the Echoes codex.
Each matches a number from the main line (4 seconds, 400 percent, 222 years, 52.9 hertz) but fills in what the main line leaves out: Lin Yu's route three years ago, the 1962 hush money, Dr. K's seventh minute, the erased name on the caretaker roll.
The fourth choice: twelve echoes + the fifth letter
After all twelve, the ending screen adds "send the twelve echoes out with the fifth letter." You stack the voices on the 34.2 difference; the surface breaks into fine rings. Three seconds later the pump answers with something longer: not one voice but seventeen names, read one by one, the last one Lin Yu. Under the bone arch Ming Yue says: "It is replying." Dr. K sets the recorder down and, for the first time, does not take notes.
It differs from the 34.2 ending: 34.2 sends one number; the fourth choice sends twelve witnesses. It isn't "better"; it simply carries the private motive to the last step. You are not settling a score for the town—you are finishing a sentence for your brother.
The four endings
| Ending | Trigger | One line |
|---|---|---|
| Publish the five letters | choose "Publish the five letters" | The sixteen names and Lin Yu enter the public record; the village loses its lease |
| Give them to the families, seal the station | choose "Give them to the families and seal the station" | The truth stays with five families; the beast story continues |
| Put the fifth letter back into the pump | enter 34.2 | You hear Lin Yu's recording; he doesn't return, but he leaves a line |
| Twelve echoes + the fifth letter | all 12 echoes, then the fourth button | The pump answers with seventeen names, the last one Lin Yu |
There is no bad ending; the difference is who you are willing to give that night to.
How you can check these numbers yourself
Every quantity above comes from what the live 25 October 2026 build actually shows, not the old guide:
- 34.2 is the difference of the two frequencies Dr. K gives you, 52.9 and 18.7; you won't find that number in any line of dialogue, file or echo.
- All four endings have their titles and text on the final choice screen, in both languages.
- The Echoes codex holds exactly twelve entries, each with a region, a picture and its text; each is just picked up by walking close.
- All four endings were walked through in both languages.