Silent Hill style Fog Barrier?

So I’m trying to figure out how to make a fog barrier so that it gradually gets foggier and darker the more the player progresses in a certain direction (so as to put an invisible wall there without it actually acting as if it’s just an invisible wall).

How would I go about doing this?

Thanks in advance!

You can add a fog to your scene and access the render settings to make it thicker as your player is moving to a specific place.

The other solution would be to use some particle system but it may get really heavy if you are covering a large zone.