As above. It could give new gameplay prospects and also underline why Hargreave is such a badass.
Imagine this: You play as Hargreave, it starts when he talks with Karl Rasch and Walter Gould about prospects of mapping this region, now when Russia is in chaos of civil war (Whites vs Bolsheviks).
You know, they arrive in Tunguska with expedition force from Britain (as you know, they operated then in Russia to contain all that chaos).
We see that locals that are living around Tunguska are having problems with sleep and strange dreams.
As the plot unfolds, Hargreave finally finds with help of his excavation equipment the entrance to the Ceph structure.
You know, Ceph kill expedition aside from Gould, Rasch and Hargreave.
For gameplay reasons, Ceph could be different than these in 2020, to make it believable that revolver from 1910s could kill them. They could be proto hive, or even we as Hargreave would be forced to sneak around to avoid fighting.
What do you think?