unity – How can I make 2D fog as a Graveyard Keeper?

I really like the fog effect of Graveyard Keeper, but I can not figure out how to do it.

It's 2D, and done in Unity. All the characters seem to be underneath & # 39; of fog, but the tops of tall trees and buildings stand out. Does it look like this:

Screenshot of fog in Graveyard Keeper.

The developer has given some information about how it is done in Gamasutra:

http://www.gamasutra.com/blogs/SvyatoslavCherkasov/20181023/329151/Graveyard_Keeper_How_the_graphics_effects_are_made.php

"As you can see, the upper part of the houses and the trees are seen from the fog, in fact, this effect is really easy to do, the fog consists of a lot of horizontal clouds scattered throughout the image. The top of all the sprites is covered with a smaller amount of fog sprites: "

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I used the information in this article, and One of the developer's tweets that included this photo.:

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I tried to recreate this fog effect. When the character moves up or down on the screen, it flashes when crossing each fog sprite:

Animated gif that shows the character moving through the fog.

What have I missed?

All sprites are in the default classification layer and have sort order 0.

The project, in Graphics Settings -> Camera Settings has the custom axis and the classification axis (0,1,0). The tree and character are in the same z position, and the fog extends over several z positions:

Oblique view of fog setting