Play this game ↗ · About this game · By alphaBETA DEV · Published 2026-06-27 · Updated 2026-09-08 · Editorial standards · Changelog

The Sunken City — Complete Walkthrough

1. About the game

The Sunken City is an ocean-horror ARG played inside a fake browser. You are the freelance journalist Shen Yu. Three months ago your father, the marine researcher Chen Yuanzhou, disappeared over the Lan City Trench. You come to Lan City with your grandmother Chen Qinglian’s belongings: a brass key stamped S.P.S.-01, a 1962 photograph, and a sentence you have heard for twenty years—

“On the night of the full moon, they will return from the sea.”

The “Underwater Palace” is not an alien city. It is the drowned town of Lan City, submerged in 1740. In 1962 the S.P.S. project built a pressure chamber onto the old bell-tower foundation; during a main-valve test the hatch sealed and seven men did not come out. In 2026 the automatic cycle restarted, and eight fishermen and your father went missing.

• Acts: 8
• Simulated websites: 20
• Collectible clues: 36, all deliverable
• Puzzles: 15
• Emails: 22
• Endings: 4 + an epilogue
• Time: 5–8 hours

The evidence board now holds 36 clues in all, and 36 / 36 means you have them. A handful of older clues that pointed at other games are gone — don't go hunting for them with an out-of-date guide.

2. Controls

• Left column: the site list. A padlock means the act has not opened yet; advancing an act opens the site.
• Search: one keyword at a time; a whole sentence usually returns nothing. Discovered keywords stay under the box.
• Evidence bar: x/36; a collectible clue enters a slot when you read its page.
• Email and notes: two separate panels; email advances the plot, notes hold your working conclusions.
• Keeper’s log: at the top of the evidence bar, eight pages unsealed one per act; with all eight, every ending gains a “tonight’s keeper” page.
• Puzzles: text input, redaction, Morse, spectrogram tuning and a four-way choice; puzzle 12 is the ending choice.

3. The eight acts

Act 1 · Arrival at Lan City

Visit the Fisherman’s Inn (night log, inn home) and the Tide Forum lights thread. Collect the anonymous email, the innkeeper’s warning and the night-light photographs. You see the lights for the first time; your father’s last voicemail contains a three-short, three-long, three-short knock.

Act 2 · Sounds from the Deep

Read the Evening News front page, the Marine Institute hydrophone page and the Wanghai Lighthouse log. The hydrophone records 52 Hz every eight minutes, sourced from the deepest point of the trench. The keeper, Zhou Dehai, says the same sound was heard in 1962.

Act 3 · The Tidal Ballad

Read the Folk Museum’s Ming scroll, Uncle Aihai’s oral history at Catch Talk, and the “Tide Prayer” in the Ancient Library. The old town drowned in 1740; the Chen family kept the lighthouse for generations; in 1962 Chen Shouyi disappeared in the undersea works.

Act 4 · The Institute’s Secret

Read the Government Portal’s S.P.S. approval, the Harbor Authority equipment anomalies, the Deep Listener’s Blog encrypted post and the People’s Hospital case report. The project built the pressure chamber in 1962; in his third progress report your father finds the seven-name list.

Act 5 · The Drowned Town

Read the Deep Sea Observatory contact log, the social media thread and the tide monitoring anomaly data. The “contact events” are knocking from inside the chamber; the frequency is rising and 15 July is the next window.

Act 6 · The Sealed Truth

Read the Geological Survey cavity report, the police archives missing list, the Dark Water Archive Elder-File-001 and Chen Yuanzhou’s private notes. The cavity is the old bell-tower foundation plus a 1962 pressure chamber; the “alien prison” was a cover story written by the project. Your father is on the missing list too.

Act 7 · The Tidal Window

Read the submersible log, the flood-gate close-up and the Sea View Church keeper register. The gate is the old town’s flood gate; its six reliefs show the 1740 flood, the move inland, the 1962 works, the 1987 reinforcement, the 2001 repair and the 2026 survey. The 1962 page has seven names, Chen Shouyi last; the 2026 page has your father and your name—“next listener”.

Act 8 · The Final Choice

On 15 July the pressure chamber begins to close. At the gate page you get four choices:

• Run the 1962 shutdown → ending A
• Connect the last recording → hidden ending B
• Stay as the listener → secret ending C
• Bring the families to the breakwater and read the names (needs 30 clues) → true ending D

If you choose “connect the recording”, one more text puzzle follows: enter the name of the last man knocking—Chen Shouyi.

4. The four endings and the epilogue

• A · Eternal Seal: three beacons at once, main valve cut, chamber vented. The sea goes quiet; your father’s voice is cut off. The man your grandmother waited for comes back as silence.
• B · Voice of the Abyss: you connect the last 1962 recording and hear seven men taking turns on the pipe. Your father says “take the names up”. You publish it; the seven of 1962 and the seven of 2026 are written into one list.
• C · Child of the Tide: you stay in the observatory and become the next listener, listening once every 22.2 hours to check the chamber is still breathing. The town knows only that the lighthouse lights each night.
• D · The Sunken City: you bring seven families to the breakwater, play the recording and read the seven names. At the seventh the knocking stops and the main valve vents on its own; the drowned town of 1740 is entered on the chart for the first time. Your grandmother’s name is added to the 1962 memorial.
• Epilogue · Return: one year later Shen Yu comes back with a new book and a recorder; a plaque on the breakwater reads “1962–2026, seven people, and the one who listened.”

5. All puzzles quick-reference table

Puzzle 13 is no longer “Tide Lord”. The old version read the 1962 recording as an alien entity; the answer is now your grandfather’s name.

6. The 36 collectible clues

Grouped by the act field (page delivery is authoritative):

• Act 0 (3): anonymous email, innkeeper’s warning, night-light photos
• Act 1 (3): evening news front page, hydrophone record, lighthouse log excerpt
• Act 2 (3): Ming scroll, tidal ballad, reef inscription photo
• Act 3 (4): S.P.S. approval, harbor anomaly record, encrypted blog post, hospital case record
• Act 4 (3): contact event log, social thread, tidal anomaly data
• Act 5 (4): seabed cavity map, missing persons report, dark-web file, cycle notes
• Act 6 (3): submersible footage, chamber countdown, church keeper register
• Act 7 (13): 1962 shutdown procedure, Chen Yuanzhou’s last message, 1962 duty roster, Shen Yu’s notes, old-town flood stele, Shen Yu’s abnormal hearing, frequency crosses critical, grandmother’s photograph, Chen keeper register, Chen Yuanzhou’s encrypted log, the old bell tower, Shen Yu’s recording notes, final frequency report

The evidence bar always reads N/36 — there is nothing numbered 37 to 51. Opening the page is enough; there is no second button to find.

7. Where people get stuck

1. The Dark Water captcha depends on how many clues you hold at that moment; advance first, then try.
2. Puzzle 13 wants “Chen Shouyi”, not “Tide Lord”.
3. The true ending needs 30 clues; the last four are on “home” pages (inn attic, lighthouse home, institute home, museum home), so do not read only detail pages.
4. The gate code follows the reliefs’ internal order; do not convert to AD years.
5. The ballad has three sources: the museum, the ancient library and Catch Talk; read all three before the true ending.

Changelog

• 31 October 2026: the older eighth-act page and the September endings page are now part of this guide, and the 52 Hz → 92 Hz reseal detail is written up here.
• 26 October 2026: rebuilt for the rewritten story. It is now about Shen Yu looking for her father and giving the man her grandmother waited a lifetime for his name back; puzzle 13's answer is now Chen Shouyi; the evidence board came down from 51 clues to 36; all four endings and the epilogue were rewritten.
• 2026-09-08: ending triggers and clue thresholds corrected.
• 2026-06-27: first version.