The Sinking City 2 Missable Checklist by Chapter

Chapter 1 — A New Day

• The 1908 house safe.
• The Star Key outbuilding, and the ERC crate in it.
• The trident obelisk sequence completed and the trident returned.
• The watergate opened, and anything it opened access to swept.
• Every clue picked up — early Dream Essence is what gets your first talents online.

Chapter 2 — The Wake-Up Call

• The room 301 safe.
• All three Lorelei chests — including room 203 with its cursed objects.
• The Printing House ERC crate in the Linotype Room.
• Printing plates A, B and C, and the A.P.H. Key doors they belong to.
• The wireless sequence completed.

Chapter 3 — A Sight For Sore Eyes

• The reception ERC crate at the hospital entrance.
• All five mask pieces.
• Every prism station, since one of them opens a wing you may not have entered.
• Both keyed wings — Vertebral and Caduceus — plus anything the Anti-Rust Acid opens.

Chapters 4 and 5

Time and Tide is the richest chapter in the game and the last one that restocks you properly:

• 1496 and 6294, both safes.
• The salt storage and the symbol padlock lockers.
• Leyden jars, the Fish Eye Key and Snowflake Key doors, and the wreck interior.

Cold Comfort is short and ends the game:

• Everything before you align the portal device — that is effectively the last point of no return.
• Spend all banked Dream Essence; there is nothing to save it for.

What counts as a missable in this game

The Sinking City 2 missable collectibles are not a category the interface labels for you — they are simply everything that lives inside a chapter you have left. That includes ERC crates you never opened, inventory upgrades on tables you never entered, evidence items, optional investigations, and the safes and side locks that hold supplies.

Story progress is never missable, and neither is anything in a safe room stash. Everything else is, including things that do not look like collectibles at all: a document you read but did not pick up, a side room you cleared of enemies but never searched, a crate you noted and meant to return to once you found a pen.

The interface will not warn you about any of it. That is the whole reason this page exists.

There is one mercy worth knowing: nothing story-critical can be lost. Every key, every code and every mechanism needed to finish a chapter is either handed to you or placed on the critical path, so a chapter can never become unwinnable. What you lose by rushing is supplies, permanent upgrades and trophy sets — painful, but never a soft lock.

How to recognise a point of no return

The Sinking City 2 does not usually warn you. The reliable tells are:

1. A boat departure the game initiates rather than one you steer.
2. A portal, ritual or dimensional transition.
3. A door that plays a long cutscene instead of opening normally.
4. An objective that says "leave" or "return".

When you see one, stop and sweep. Chapter cleanup costs ten minutes and saves a second playthrough — although you will be doing one of those anyway for the codices.

It is worth being blunt about the stakes, because The Sinking City 2 is unusually unforgiving here. A missed inventory upgrade is permanent for that run. A missed collectible set can lock a trophy for the entire playthrough. And because chapters close on story beats rather than on an explicit warning screen, the moment you notice is usually the moment after it is too late. Ten minutes of cleanup per chapter is the whole defence.