This walkthrough replaces the four-act overview with a per-chapter anchor for Devil's Reef, Akeley Memorial Hospital, Redemption Church, Fish Market, and the Portal Room, plus a compact puzzle table that names every code, hint source, and optional-investigation trophy. Codes below are sourced from the public walkthroughs listed in the Sources block (TreyexGaming Puzzle Solutions Guide, PowerPyx, GameSpew, GamePressure Chapter 1, and Gamer Social Club's 100% achievement guide). Where a code requires carrying supplies across districts, the table calls out the prep step explicitly so you don't permanently skip the related trophy.
Chapter 1: Devil's Reef (Prologue Demo)
Devil's Reef opens the four-act campaign and is also the Prologue demo level that has been live on Steam since 10 Jun 2026. The chapter has two gated puzzles with codes you cannot recover mid-chapter if you skip the prep step. - **Devil's Reef Safe (Captain's logbook hint)**: Captain's logbook sitting on the desk in the Captain's office. Read the entry first; it gives the explicit number. Without that hint the code stays opaque. - **Apartment 5 Wall Safe — code `1908`**: First gated safe of the chapter. Open it for `The Inheritance` investigation trophy. - **Gate Fuse Box (Electrical Fuses from Radio Shop)**: Pick up the Electrical Fuses from the second-floor Radio Shop. The fuse box is on the gate; place each fuse in the slot that matches the circuit diagram on the box and then pull the right-hand lever to open the gate. The Electrical Fuses also progress `The Inheritance`. Attribute the chapter's codes to the TreyexGaming Puzzle Solutions Guide and the PowerPyx Devil's Reef walkthrough.
Chapter 2: Akeley Memorial Hospital
Akeley Memorial is the second act's primary survival-horror region. It carries the second weapon pickup (the Submachine Gun) and the longest stretch of optional investigations in the chapter. - **Trident puzzle (Redemption Church entry step)**: Find the Church Key to unlock the church, then locate the Trident at the rear of the church. Go to the obelisk behind the church and rotate each section until all symbols align, validate, and wait for three lightning strikes to charge it. Carry the Trident back to the top floor of the church to complete the activation. This progresses `The Other Gods`. - **Cursed Press (Printing House)**: Collect Printing Plates A, B, and C from the surrounding rooms. Place them on the press in the Gold or Silver configuration. The Gold choice unlocks the Cutter's Sturdy Stock shotgun accessory; the Silver choice yields 2 Dream Essence. This progresses `The Red Press`. - **Room 301 Safe (Devil's Reef Hotel) — code `2137`**: The code is hidden across two evidence pieces inside the hotel: the "Baby, One More Tide" lyrics on a ground-floor VIP table (each lyric maps to a digit: 2 wings / 1 tail / 3 octopus hearts / 7 deadly sins) and Heloise's Letter in Room 303. The reward is Voss's Target Grip, handgun ammo, and shotgun shells. This progresses `The Siren's Call`. - **Ventilation System — sequence `1-1-2-2-2-2-3-3-Red switch-1`**: Flip the numbered breakers in this exact order, throw the Red switch at the end of the sequence, then flip breaker 1 once more. Restarting from the safe room is cheaper than guessing because wrong inputs reset the chain. Attribute the chapter's codes to the TreyexGaming Puzzle Solutions Guide.
Chapter 3: Redemption Church and Akeley Hospital morgue
Chapter 3 layers the Redemption Church investigation over the Akeley Memorial morgue side, and every code here gates a missable investigation. - **Locked Storage code — `1308`**: Located on the basement (-1F) of Akeley Memorial Hospital. You need the Anti-Rust Acid pickup before the code prompt will accept input; without the acid the panel is locked and the puzzle blocks. This unlocks `The Vault`. - **Three Prism Stations (Hospital)**: Blue Treatment / Yellow Priest / Pink Manipulations. Each station is a ring-rotation puzzle, not a number code; rotate the three rings at each station until the Occult Symbols line up with the coloured marker. The Manipulations Room is in the basement. - **Wireless Room brain frequencies — `13 -> 05 -> 36`**: Three talking brains in the Wireless Room. Enter each frequency separately and confirm with the central button between brains. The in-game evidence clues the order: Pence (13, an unlucky number between 10-20), Dunwich (5, half the rounded-ten of the first), Ambrose (36, double the sum of the first two). This progresses `The Whisperers`. Attribute the chapter's codes to the TreyexGaming Puzzle Solutions Guide.
Chapter 4: Fish Market
The Fish Market chapter hosts four missable investigations and the late-game weapon pickup, so pacing matters: do the locker-room and weighing-station prep before the second Leyden Jar. - **Buoy combination (`The Drowned`)**: `Lighthouse -> Ropes -> Starfish -> Octopus` press order. This is the buoy puzzle that opens `The Drowned`. - **Sixteen Punishments press order — `I -> IV -> IX -> XVI`**: The press can be triggered in any order as long as those four are pressed. This unlocks `The Damned`. - **Memory Safe — code `6294`**: Found mid-chapter in the Salting Room area. Required to unlock a follow-up clue for `The Damned`. - **Strange Statue shoot order — `Kneeling Woman -> Octopus -> Sea Creature -> Time -> Jar`**: Shoot the statue reliefs in this exact order; a wrong shot resets the sequence. The statue is part of the same Salting Room side as the Memory Safe. - **Locker Room Safe — code `1496`**: Bring the bolt cutters (found earlier in the chapter) to the locker room; the safe is reachable only after the cutters are used. This unlocks `The Drowned` follow-up. Attribute the chapter's codes to the TreyexGaming Puzzle Solutions Guide.
Chapter 5: Portal Room
The final chapter is a single puzzle that wraps the campaign. There is no chapter-or-replay mechanism after this point, so missing the prep step means you do not finish. - **Portal Room activation**: Pick up the Engraved Pod from across the northern bridge into the Portal Room chamber. Place the Pod in the central machine, rotate the side / top / bottom sections until the patterns align, then validate. The Portal opens and triggers the final sequence. There is no numeric code here; the puzzle is alignment-based. Attribute the chapter's steps to the TreyexGaming Puzzle Solutions Guide.
Compact Puzzle and Code Index
Every gated code and sequence in this walkthrough, with the chapter anchor, the hint source, and the optional-investigation trophy it unlocks: | Chapter | Puzzle | Code / Sequence | Hint source | Optional-investigation trophy | |---|---|---|---|---| | Chapter 1 | Devil's Reef Safe | Captain's logbook entry | Captain's office logbook | (story) | | Chapter 1 | Apartment 5 Wall Safe | `1908` | TreyexGaming | The Inheritance | | Chapter 1 | Gate Fuse Box | Electrical Fuses -> circuit slots -> lever | Radio Shop, second floor | The Inheritance (carry) | | Chapter 2 | Trident / Church Obelisk | Rotate to align symbols, then validate, wait for 3 lightning strikes | Church Key + obelisk rotation | The Other Gods | | Chapter 2 | Cursed Press (Printing Plates A/B/C) | Gold or Silver choice | TreyexGaming | The Red Press | | Chapter 2 | Room 301 Safe | `2137` | "Baby, One More Tide" lyrics + Heloise's Letter | The Siren's Call | | Chapter 2 | Ventilation System | `1-1-2-2-2-2-3-3-Red switch-1` | TreyexGaming | (side prep) | | Chapter 3 | Locked Storage (morgue -1F) | `1308` | Anti-Rust Acid pickup required | The Vault | | Chapter 3 | Prism Stations (Blue / Yellow / Pink) | Ring-rotation alignment | TreyexGaming | (side) | | Chapter 3 | Wireless Room brain frequencies | `13 -> 05 -> 36` | TreyexGaming | The Whisperers | | Chapter 4 | Buoy (`The Drowned`) | `Lighthouse -> Ropes -> Starfish -> Octopus` | TreyexGaming | The Drowned | | Chapter 4 | Sixteen Punishments press order | `I -> IV -> IX -> XVI` | TreyexGaming | The Damned | | Chapter 4 | Memory Safe | `6294` | TreyexGaming | The Damned (follow-up) | | Chapter 4 | Strange Statue shoot order | `Kneeling Woman -> Octopus -> Sea Creature -> Time -> Jar` | TreyexGaming | The Damned (follow-up) | | Chapter 4 | Locker Room Safe | `1496` | TreyexGaming | The Drowned (follow-up) | | Chapter 5 | Portal Room | Engraved Pod alignment + validate | Across the northern bridge | (finale) | The no-chapter-replay constraint is what makes this table load-bearing: skipping the optional investigation means missing the related trophy on the first playthrough and forces an NG+ run for the missing 18 missable achievements (covered on the [/achievements](/achievements) page).
Sources
[TreyexGaming - The Sinking City 2 Puzzle Solutions Guide](https://www.treyexgaming.com/the-sinking-city-2-puzzle-solutions-guide) - `media/interview` - checked `2026-08-27` - Per-chapter puzzle solutions and codes (Apartment 5 Wall Safe `1908`, Room 301 Safe `2137`, Ventilation `1-1-2-2-2-2-3-3-Red-1`, Locked Storage `1308`, Wireless Room `13 -> 05 -> 36`, Buoy `Lighthouse -> Ropes -> Starfish -> Octopus`, Sixteen Punishments `I -> IV -> IX -> XVI`, Memory Safe `6294`, Strange Statue `Kneeling Woman -> Octopus -> Sea Creature -> Time -> Jar`, Locker Room Safe `1496`, Portal Room Engraved Pod alignment). [Gamer Social Club - The Sinking City 2 100% Achievement Guide](https://gamersocialclub.ca/2026/08/18/the-sinking-city-2-100-achievement-guide) - `media/interview` - checked `2026-08-27` - The 18 missable achievements grouped into weapons, investigations, NG+ collectibles, and a single-playthrough completion route. [PowerPyx - The Sinking City 2 Devil's Reef walkthrough](https://www.powerpyx.com/the-sinking-city-2/devils-reef-walkthrough/) - `media/interview` - checked `2026-08-27` - Devil's Reef chapter step-by-step and the Radio Shop Electrical Fuses pickup order. [GameSpew - The Sinking City 2 Devil's Reef walkthrough](https://www.gamespew.com/the-sinking-city-2/walkthrough/devils-reef/) - `media/interview` - checked `2026-08-27` - Devil's Reef puzzle anchors used as cross-reference for the Chapter 1 codes. [GamePressure - The Sinking City 2 Chapter 1 Devil's Reef](https://www.gamepressure.com/the-sinking-city-2/chapter-1-devils-reef.htm) - `media/interview` - checked `2026-08-27` - Chapter 1 puzzle context used to cross-reference the gate fuse box and the Apartment 5 wall safe. [The Sinking City 2 on Steam](https://store.steampowered.com/app/2825860/The_Sinking_City_2/) - `official/store` - checked `2026-08-27` - 18 Aug 2026 worldwide launch, Steam AppID 2825860, four-act structure framing. [TrueAchievements - The Sinking City 2 achievements](https://www.trueachievements.com/game/The-Sinking-City-2/achievements) - `wiki/reference` - checked `2026-08-27` - 23-achievement total and the live source-of-truth achievement list.