Games like In My Head
Games like In My Head include Outlast, Poppy Playtime, Layers of Fear (2016), Firewatch, and What Remains of Edith Finch. We matched them by the tags players give In My Head on Steam (Adventure, Horror, Psychological Horror, Walking Simulator, and First-Person): closest matches first, and among equally close ones the better-known games.

Outlast
Shared: Horror · First-Person · Psychological Horror

Poppy Playtime
Shared: Horror · First-Person · Psychological Horror

Layers of Fear (2016)
Shared: Horror · Psychological Horror · Walking Simulator

Firewatch
Shared: Adventure · Walking Simulator · Atmospheric

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

Mouthwashing
Shared: Horror · Psychological Horror · Atmospheric

Visage
Shared: Horror · Psychological Horror · Adventure

Blair Witch
Shared: Adventure · Horror · Psychological Horror

MiSide
Shared: Psychological Horror · Horror · First-Person

SOMA
Shared: Horror · Psychological Horror · Atmospheric

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

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

Summer of '58
Shared: Horror · Psychological Horror · Walking Simulator

ROUTINE
Shared: Psychological Horror · Adventure · Atmospheric

Phasmophobia
Shared: Horror · Psychological Horror · First-Person

From The Darkness
Shared: Horror · Psychological Horror · First-Person

Amnesia: A Machine For Pigs
Shared: Horror · Walking Simulator · Psychological Horror

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

Little Nightmares II
Shared: Adventure · Horror · Psychological Horror

Little Nightmares
Shared: Horror · Adventure · Atmospheric

Welcome to Kowloon
Shared: Horror · Adventure · Psychological Horror

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

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

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