fog masking

Hello there, i’ve got a big city objects in the background and i need to set a fog around the player, so the city does not affect by the fog, is there a way to mask the city layer somehow?

I don’t know a way to do it with layers, but you can edit your city material(s) so that they can’t be affected by fog.
Just add this line in the SubShader section of your shader: Fog {Mode Off}. E.g.:

SubShader {
		Tags { "RenderType"="Opaque" } //Or whatever
		LOD 200 //Or whatever
		Fog {Mode Off}