Best way to do 'Fog' for a low poly/rez game

My friends and I are working on a small project where a player is inside an abandoned space station. We want there to be fog obscuring the player's vision (then a mini game tied to clear it, but thats mostly figured out already). What would be the best way to go about doing this, via Niagara, Volumetric fog, or something else? I've tried both and, they seem like too much (and eat up performance). Something like what the OG Silent Hill would be perfect, but so far none of the tutorials or documentation i've been able to dig up has pointed me in the right direction.

I should also add that we're using a post-process, as well as low-resolution assets, to make it look like a PS1-era game.