| "I once thought I could save the world... now look at it"
— Spoilers for Deus Ex: Mankind Divided follow!
If you do have the cure and want to save everyone, including Miller (and get the He's [Not] Dead, Jim achievement) you can do it if you move fast. However, this walkthrough will assume you do not have the cure (if you do, you can go ahead and use it now on Miller).
If you choose to face Marchenko first or want to bypass the guards to the delegates, go back to the reception hall and the door to the exhibition area is now accessible. Once you start the fight, go to the second floor where the turret and mines are. There is a switch underneath the bar table that opens up a secret entrance to the VIP area. Once you save the guests, go back through the hidden door (it is part of the green monitors behind the mounted camera) and continue the fight. You can also take care of Marchenko first then use the hidden door, just make sure to do it quickly as possible to save them.
If you choose to save the delegates first, run through the door in the back of the catering room into a heavily guarded area. You can either sneak through vents, fight your way through, or, if you have a ton of biocells, the Icarus Landing, maxed out leg augmentations, and maxed out glass-shield cloak, you can run through without raising suspicion (you will need about 10 biocells if you run through, just to be safe). The most straightforward path is to run down the hall with the 2 cloaked guards and turret, down the hall to the right, to the left of the stairs, and go all the way to the end and turn right where the elevator is at the far end. If you do not want the guards becoming suspicious or alarmed, do NOT call the elevator. Instead, go through the door that is next to the window with the keycard and use Icarus Landing to jump down the elevator shaft and enter through the open hatch. Take it to the VIP rooms. If you gave Alex the evidence from M7: The Rucker Extraction, she will tell you a code for the door you will need to get through. Get to the floor and run down the hall to the locked door. Use the code, a multi-tool, or just hack it to get in and a cutscene will play out. If you were quick enough, you will stop them from taking a sip.
Now, once the delegates have been rescued, use the hidden door in the room (it is part of the green monitors behind the mounted camera) and use the path to get into the exhibition hall. The game will go to a cutscene, placing you in the usual spot as if you went through the main doors rather than the hidden one upstairs. If you were fast enough, Marchenko will be none the wiser that you saved the delegates. There are several quick options (both lethally and non-lethally) to take him out, like if you got Allison Staněk's switch or Damocles' Sword (Marchenko's killswitch). Take him out however you see fit and the game will switch to the ending, giving you the achievement.
Tips and Strategies Edit
- There are a number of factors that will decide how easy or hard this will be to get.
- If you got Allison's switch and/or Damocles' Sword, you can confront Marchenko first and use it, then use the hidden door to save the delegates before going back to deal with him (if you did not use his killswitch).
- If you have the right augments, accessing the hidden door in the exhibition hall makes it far easier to do M16: Stopping Marchenko first as you just need to get past a turret, laser grid, and mines, rather than a bunch of guards and turrets if you took the delegate route first.
- If you did not set off any alarms during M15: Securing the Convention Centre, you will have 10 minutes to save the delegates and run to meet Marchenko. If you did set them off, Marchenko will give you less time (unsure how much less).