Play this game ↗ · About this game · By alphaBETA DEV · Published · Updated · Editorial standards · Changelog

Tide Sound Archives: The 222-Year Cycle, the Tide Station and the Unlisted Eighth Name

Tide Sound Archives: The 222-Year Cycle, the Tide Station and the Unlisted Eighth Name
Header illustration generated for this article with an AI image model. It is promotional art, not an in-game screenshot.

This article covers only what exists in the 2026-10-26 version. The old “chapter six: Beyond the Tide”, the six-frequency list and the global frequency network are gone; if you see them elsewhere, that material is obsolete.

This guide was checked against the game on 31 October 2026. The screenshots below are real gameplay; the opening image is an AI illustration and is labelled separately.

A water-damaged field notebook open on a desk, its pages covered in hand-drawn tide curves; a brass tide gauge and a paper-tape reel beside it, a lighthouse beam crossing the rain outside. This is an illustration, not a game screenshot

AI illustration generated with SenseNova. It is not a game screenshot.

1. There is no chapter six

Tide Sound Archives has six entries in its chapter table:

  1. Prologue · An anonymous email
  2. Chapter One · Anonymous report
  3. Chapter Two · Beneath the lighthouse
  4. Chapter Three · Project Tide
  5. Chapter Four · Signal and echo
  6. Finale · Names

The finale adds no new site. The old “one more chapter after the finale” epilogue took part in no choice and delivered no collectable clue; it was removed in the 2026-10-26 rewrite.

2. Where the 222-year page is

It sits under the history archive, act: 4, but it does not appear automatically with the chapter. The path is:

  1. Get FM91.7 at the radio first (opening the Frequency Allocation Table or parking the tuner on 91.7 both deliver it).
  2. Open search and enter frequency (in the Chinese UI, 频率).
  3. Open the result “Lancheng City History Archive — 222-Year Frequency Cycle Research”.

Searching “frequency” returns two results: the radio Frequency Allocation Table on top, and the 222-year page below it. The second title contains “222-year” and “tide station”; do not click the wrong one.

Two results for “frequency”: the FM 91.7 Frequency Allocation Table on top, and “222-year frequency cycle: tide station, 18.7 Hz and seven disappearances” below

Open the page and "The 222-year frequency cycle" appears in the clue panel — there is no second button to find. The final chapter asks for the other ten clues, not this one. You can still finish A/B/C on the main line, but D stays out of reach.

3. What the three rows actually say

The core table on the page has three rows:

YearTideLocal record
1582August spring tideThe Wanli earthquake: “the sea boiled for three days, the tide sounded like thunder”; epicentre off Eagle Beak Point
1804August spring tideSeven fishing boats failed to return on the same day; the fishery archive says only “lost to the tide”
2026Next coincidenceLast line of the decoded FM 91.7 message: NEXT OPENING: 2026

The arithmetic is plain: 1582 + 222 = 1804; 1804 + 222 = 2026. All three fall in the August spring tide. The September 2003 disappearances fall in the same month, which is why Su Xiaowen plotted “tide — 18.7 Hz — disappearances” on one sheet of graph paper.

The 222-year frequency cycle research page: the three-row table, the fifteen-second tide gauge and the 18.7 Hz note, inside the archive page layout

This table is not a “global resonance”. It is a local Lancheng tide record. The 1582 and 1804 rows are the parts the local gazetteers can support; the 2026 row comes from the decoded message and is the story’s “next”. Only together do they make a cycle.

4. Fifteen seconds: a beat, not a broadcast

The tide station’s automatic gauge sends a pulse every fifteen seconds. The looping FM 91.7 signal is also fifteen seconds. In her notebook Su Xiaowen writes:

“It isn’t transmitting. It’s setting its watch by the tide.”

That line reverses the whole “mysterious signal” reading: it is not someone undersea sending a message; it is a facility waiting for a tide height. On 11 September 2003 the typhoon pushed the tide to 2.87 metres, just past the line she had drawn. The facility started that night, and the seven went down one after another. They did not choose the well; the well was waiting for a tide height.

This is also why 18.7 Hz and 91.7 MHz have to be kept apart: 18.7 Hz is the underground facility’s infrasound frequency; 91.7 MHz is the shell that lets an ordinary radio receive it. They are not two ways of writing one number, and the gap is not a simple integer ratio.

5. The unlisted eighth person

The seven names are Zhao Mingyuan, Lin Haiyan, Zhou Jianguo, Chen Lei, Fang Zhiwen, Su Xiaowen and Ma Jun.

Chen Zhou is not on the list. He was the lighthouse keeper. On 12 September 2003 he went down to look for them and would not say what he saw when he came back; after his last oral-history interview in 2005 he disappeared, and was declared dead in 2011.

So there is one more person outside the seven, with no number. The finale line “Chen Zhou is the unlisted eighth person” is assembled from this page and the keeper’s log. Note what he is not: he is not an eighth experimental subject, and not a substitute on the list. He is a witness who went down, came back alive, and still vanished.

6. Which ending it affects

Only D, The Night Watch. The finale looks for two things: that you actually decoded the looping signal on the radio page, and that you read this 222-year page into the clue panel. Without both, the finale offers A/B/C only. Collecting all ten tapes adds E, The Roll Call, which has nothing to do with this page.

If you only follow the main line, A/B/C do not need it; but you miss the page that reads most like “the notes she left behind”, and you miss the way into D.

7. Claims that are now obsolete

8. Try it yourself

Changelog