The Sinking City 2 ERC Activator Pen Locations

The rule, stated plainly

This is the most searched mechanic in The Sinking City 2's first week, and it is simpler than it looks. Crates are locked by design. The key is a consumable pen. Pens are scattered around the same level as the crates, in the ordinary places this game hides things: desks, drawers, bodies and side rooms that the objective marker does not route you through.

There is no upgrade, talent or tool that removes the requirement. If a crate is shut, you need a pen.

Where pens turn up

• On desks and workbenches in administrative rooms — registries, offices, reception areas.
• On bodies. The Sinking City 2 puts a remarkable amount of important loot on corpses, which read as scenery in the dark.
• In side rooms off the critical path. If you are following objective markers exactly, you will finish chapters with unopened crates.

Because pens and crates are placed as pairs, the useful habit is to note a crate's location the moment you find it and keep sweeping rather than backtracking immediately.

How many pens do you need?

One per crate you intend to open, which in practice means all of them: crates hold ammunition, weapon attachments and inventory upgrades, and the upgrades are permanent. A missed pen is a missed crate is a missed upgrade.

Unused pens stay in your inventory, so carrying a spare into the next area is fine — but a spare at the end of a chapter is a warning sign, because it means a crate went unopened and there is no chapter select.

If you have left a crate behind

Inside the current chapter, go back — backtracking within a chapter is unrestricted. Once the chapter has closed, the crate is gone for this run and will only be available again in New Game Plus.

That is not fatal. The game is beatable without every crate, and difficulty is adjustable at any time from the pause menu if resources get tight — see difficulty settings. Lowering the difficulty for one encounter and putting it back afterwards is a legitimate way to survive a bad supply run, and it costs you nothing on the trophy side.

Common mix-ups

• Pens are not keys. The named keys — Star, Staff, Vertebral and the rest — open doors, not crates. They are listed on the keys page.
• Crates are not safes. No dial, no code. The five numeric safe codes are a separate system.
• A pen is consumed on use. You cannot reuse one across two crates.

The confusion is understandable, because The Sinking City 2 runs four separate lock systems at once: codes, symbol mechanisms, named keys and activator pens. Each has its own prompt, and learning to read the prompt saves more time than memorising any individual solution — a crate prompt mentions the activator, a safe shows a dial, a mechanism opens an interface, and a keyed door simply says locked.