The Residuum Experiment is an interesting mystery to solve in The Complex in Deathloop. This can be first found at the very start of the game, in Wenjie’s Laboratory Annex, but it’s a good idea to hold off on doing this one until you’ve got some resources. Solving the Residuum Experiment requires taking a Residuum sample from the Control Center to the Annex, while fighting a whole lot of Eternalists – not an easy task if you don’t come prepared.
Residuum Experiment – The Complex
The Residuum Experiment can be found inside the Annex in The Complex. This appears to be two machines beside one another, one with a vertical glass tube and the other with an array around a middle isolation chamber. The glass tube can be raised using the crank-wheel, but working out how to solve it can be tricky.
In order to solve the Residuum Experiment, you must take the Residuum sample (which is labelled Residuum Experiment) from the Loop Control Center to the Annex and insert it into the contraption. The trouble is that once you pick up the Residuum sample, a dozen Eternalists will spawn and the doors in the Loop Control Center will lock, meaning your only way out is to fight out. The problem is that one stray bullet will smash the Residuum sample and you will need to restart the day. Completing this challenge requires a bit of setup, specifically, collecting a crank-wheel, placing turrets, hacking doors, and setting up some trip mines.
Begin by taking the crank-wheel from the Annex to the Loop Control Center. The wheel is on the table beside the contraption. Put the crank-wheel into the Residuum sample (to the right of the controls). Check out our guide on where to find the crank-wheel if you're struggling.
Now, you should go out the door behind where the projector is at the start of the game (this is the quickest way to the Annex but will be locked once you start the process). Go out the door and let the security sensor spot you, this will cause the door to lock. Quickly hack the security camera and the door – both of these you now control.
Continue around the bunker, hacking turrets as you go. The idea is to set up some turrets at key areas to kill the Eternalists that spawn. Place one turret on the box outside the Annex and another turret inside the Loop Control Center, facing the stairs. You can also place some trip mines around the long way.
When everything is set up and the turrets are on, you can enact the plan. The idea is to grab the Residuum, place it near the door that is the quickest path to the Annex (even though it’s locked) and then run around the outside of the building and hack your way back into the Loop Control Room. Doing this ensures the Residuum sample is safe from the Eternalists while the turrets gun down your enemies.
As soon as you get inside the Annex with the Residuum sample, place it into the Residuum Experiment, lower the glass tube, and press the button on the left contraption. This will start the process of making a trinket! When it’s done, grab your new, shiny trinket and remember to infuse it.
Solving the Residuum Experiment in The Complex and getting the Residuum sample safely to the Annex can take a bit of work. With the right setup and some smarts, you should be able to complete the experiment and claim your new trinket. Check out the Shacknews Deathloop guide for more help with the game’s many secrets.