Games like Whispering Fog
Games like Whispering Fog include Mouthwashing, Visage, Outlast, Poppy Playtime, and Layers of Fear (2016). We matched them by the tags players give Whispering Fog on Steam (Horror, Psychological Horror, Dark, Atmospheric, and First-Person): closest matches first, and among equally close ones the better-known games.

Mouthwashing
Shared: Horror · Psychological Horror · Atmospheric

Visage
Shared: Horror · Psychological Horror · Dark

Outlast
Shared: Horror · Psychological Horror · First-Person

Poppy Playtime
Shared: Horror · Singleplayer · First-Person

Layers of Fear (2016)
Shared: Horror · Psychological Horror · Atmospheric

SOMA
Shared: Horror · Psychological Horror · Atmospheric

Outlast 2
Shared: Horror · Psychological Horror · First-Person

No, I'm not a Human
Shared: Horror · Psychological Horror · Singleplayer

Summer of '58
Shared: Horror · Psychological Horror · Atmospheric

Five Nights at Freddy's
Shared: Horror · Psychological Horror · Singleplayer

Still Wakes the Deep
Shared: Horror · Psychological Horror · First-Person

MiSide
Shared: Psychological Horror · Horror · First-Person

Blair Witch
Shared: Horror · Psychological Horror · First-Person

Little Nightmares II
Shared: Horror · Dark · Singleplayer

Fears to Fathom - Ironbark Lookout
Shared: Horror · Psychological Horror · Atmospheric

Phasmophobia
Shared: Horror · Psychological Horror · First-Person

POOLS
Shared: Psychological Horror · Atmospheric · Walking Simulator

Garten of Banban
Shared: Horror · Psychological Horror · First-Person

Buckshot Roulette
Shared: Dark · Horror · First-Person

What Remains of Edith Finch
Shared: Atmospheric · First-Person · Walking Simulator

From The Darkness
Shared: Horror · Psychological Horror · Dark

Welcome to Kowloon
Shared: Horror · Psychological Horror · Atmospheric

Little Nightmares
Shared: Horror · Atmospheric · Dark

ROUTINE
Shared: Psychological Horror · Atmospheric · Singleplayer