Awesome! I had been working on a similar project couldn't figure out the snow on the trees for the life of me! It's great to see how you approached it. The work look great! Thanks for sharing your process.
I believe author would be surprised that it's not american, but soviet bunker :)
Marmoset Toolbag 2: Skin Shader Tutorial
Learn how to use skin shader in Marmoset Toolbag 2.