Half-Life: Hostile Takeover is a mod aiming to recreate the abandoned HL1 expansion made by 2015 inc.
Just regular Scientists from Allied Processing. Concept Art still WIP and there's will be more variations of them.
By the way, also you can join our discord server: Discord.gg
Scientist on the top left: Mr. Borat.
Scientist on the top right: Eddie Murphy.
Scientist on the bottom left: Barney Calhoun?
Scientist on the bottom right: I don't know what facial of this scientist was inspired on?
We'll see in the near future.
Actually, I think the bottom left looks a bit like Dr. Kawashima from the Brain Age series
I am pretty sure the bottom-left scientist is Jeff Goldblum, specifically his part in Jurassic Park?