In the alternative ending, both Miller and Artyom die from radiation poisoning and are stuck in purgatory on the Aurora for the rest of eternity.
There, it's revealed that the Dark Ones have a nest in the botanical gardens and Colonel Miller has a plan to blow up the hive.
The pair test negative for the virus, locate the Dark One a child with the help of a wanderer named Khan, and head back to Polis to find a peace conference is taking place between all of the factions.
Sensing there's a group of hibernating Dark Ones within D6, the child uses telepathic abilities to trick Soviet Red Line Chairman Moskvin into admitting the conference is a diversion, and the Rangers head to D6 for a final confrontation.
Amouranth also claims to make £1.
Artyom decides to head back to Moscow to find survivors and reveal the truth of the outside world.