The Callisto Protocol: How to Unlock the Commonality Achievement

Duncan Cole is the result of a years-long project to make the most conspiratorial human on record. From the moment he shows up in The Callisto Protocol, he’s obviously up to something, but the game’s a little cagey about exactly what.

There are a couple of secret rooms found over the course of the game that can shed some light on what’s really happening with the biophage outbreak. While neither of them provide a must-have clue, they do provide some ominous context. More importantly, if you find and visit them both, it unlocks the gold trophy/50G achievement The Commonality.

Here’s where to find Duncan Cole’s secret boardrooms in Black Iron Prison.

What to Do to Unlock The Commonality in The Callisto Protocol

Neither of the secret boardrooms in Black Iron are really that well-hidden. Their challenge comes from how thorough you are about searching your environment, as both boardrooms are well off the beaten path and require a little bit of effort to reach.

In both boardrooms’ case, they’re worth the detour, as they both contain a chest full of random resources, such as Callisto Credits, salable contraband, or ammunition, in addition to an audio log. In order to unlock the trophy/achievement for them, all you have to do is find them and walk in.

Chapter 3: Aftermath

The first of the two boardrooms is found in Chapter 3, right after you open up Black Iron’s laundry room.

There are two doors to choose from in here. If you go right, you’ll find some resources in the washroom.

Go left, and you’ll have a choice to make between going through the door to Maintenance B414 or investigating a seemingly empty room in front of Supply B426. To get The Commonality, you’ll want to check the latter.

You can access the empty room by Supply B426 by either shivving the lock on the door or slipping through the open vent. Either way, you’ll find a salable Energy Converter inside, as well as another open vent at floor level.

Crawl through that vent to find an old tunnel. Follow it down until you have a chance to drop through a hole in the floor, then keep going down the hall until you see a half-open door at its end. Slip through that door to find a chest of resources and an audio log on the back table of the room.

To go back the way you came, climb the ladder on the side of the nearby elevator shaft. This will return you to Supply B426, where you can unlock the door from inside and carry on with the stage.

Chapter 6: Below

The trick on the second hidden boardroom is to still be checking the cracks in the walls to see if Jacob will go through them, even though there are several in this chapter that are biophage-only.

Make your way through this stage as you normally would, up until you reach the balcony outside the Power Reactor room. If you slide through the broken wall nearby (above), you’ll enter a secret side tunnel that’s initially nothing weird, but eventually lets you drop into some kind of biophage spawning ground.

This is one of the more claustrophobic experiences in Callisto, but you can follow the tunnel up to a point where you’ll find another boardroom. While the door’s not open enough to let you in, you can slip through the hole in the wall next to it. Watch out for the head trap in front of the high table.

Or, you know. Don’t.

Either way, entering this boardroom should make The Commonality fire. You can also loot an audio log off the table, along with a chest of resources and several stray credit chips on the side tables.

To get out of here, you can follow a side tunnel nearby that’ll return you to the Power Reactor room.