Games like Lost Souls
Games like Lost Souls include Mouthwashing, Sally Face - Episode One, Outlast, SOMA, and Summer of '58. We matched them by the tags players give Lost Souls on Steam (Horror, Psychological Horror, Atmospheric, Psychological, and Adventure): closest matches first, and among equally close ones the better-known games.

Mouthwashing
Shared: Horror · Psychological Horror · Atmospheric

Sally Face - Episode One
Shared: Psychological Horror · Horror · Adventure

Outlast
Shared: Horror · Atmospheric · Psychological Horror

SOMA
Shared: Horror · Psychological Horror · Atmospheric

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

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

Hellblade: Senua's Sacrifice
Shared: Atmospheric · Psychological · Horror

Phasmophobia
Shared: Horror · Psychological Horror · Supernatural

Bad Parenting 1: Mr. Red Face
Shared: Horror · Psychological Horror · Adventure

What Remains of Edith Finch
Shared: Atmospheric · Walking Simulator · Adventure

SILENT HILL 2
Shared: Horror · Psychological Horror · Atmospheric

The Medium
Shared: Horror · Psychological Horror · Adventure

DON'T SCREAM
Shared: Horror · Psychological Horror · Atmospheric

Darkwood
Shared: Horror · Psychological Horror · Adventure

Little Nightmares II
Shared: Horror · Adventure · Atmospheric

Poppy Playtime
Shared: Horror · Psychological Horror · Dark

Firewatch
Shared: Atmospheric · Adventure · Walking Simulator

Alan Wake
Shared: Horror · Adventure · Atmospheric

Amnesia: A Machine For Pigs
Shared: Horror · Atmospheric · Psychological Horror

Welcome to Kowloon
Shared: Horror · Psychological Horror · Atmospheric

Still Wakes the Deep
Shared: Horror · Psychological Horror · Walking Simulator

Little Nightmares
Shared: Horror · Atmospheric · Adventure

God's Basement
Shared: Horror · Psychological Horror · Atmospheric

Visage
Shared: Horror · Psychological Horror · Atmospheric