A substance I've just wrapped up after having a bit of a horror binge recently. I started out wanting to create something with specific structures such as the spine, and it evolved from there.
I used the various options I'd built into the substance graph to output a few maps which I then used to texture a simple tunnel environment in Unreal with mesh vertex paint and material tessellation. I made use of subsurface scattering in both UE4 and Toolbag 2 to enhance the fleshy appearance.
Everything for the materials was created in Substance designer.