Directional light seems shines through meshes despite two-sided shadows

Am working on a 2.5D sidescroller game. That effectively means I have a (procedurally generated) mesh that is appearing as if cut in half.
The terrain basically consists of a surface (sand-like yellowish in the images) and caves (dark gray, reflective) as well as a vertical texture that is perpendicular to the cam (a mossy rocks texture here).

Now I want to have a directional light that illuminates the surface as if it were the sun but leaves the caves completely in the dark.

For some reason the directional light is brightening up the entire caves too though although there should not be a line of sight to the directional light plane.

“Two sided shadows” are activated for all meshes!
Have also put the ambient color of the scene to black, in case that would cause the issue but it does.

Basically what I’d like is to have the surface illuminated like here:

But the caves and the parallel plane dark like here:

Of course the caves would be later illuminated by point lights originating from decorations and the player etc.

Anyone have an idea?
Huge thanks in advance :slight_smile:

Assuming the directional light is the only light in the scene (and isn’t facing onto the side of the scene), you can go into your lighting settings and set your ambient and reflection intensity to 0, as this to me looks more like ambient light than it does directional light.