sewonist.com
http://in2gpu.com/2014/07/22/create-fog-shader/
My take on shaders: Firewatch multi-colored fog
http://blogs.unity3d.com/cn/2015/05/28/atmospheric-scattering-in-the-blacksmith/
http://stackoverflow.com/questions/52238392/how-can-simple-low-poly-stylistic-fog-lighting-be-achieved-in-unity-3d
Best Free Unity Assets – Over 200 Curated Quality Assets
https://github.com/OCASM/SSMS