Games like Once Upon A Mind - A Little Too Friendly
Games like Once Upon A Mind - A Little Too Friendly include What Remains of Edith Finch, Firewatch, Layers of Fear (2016), SOMA, and Fears to Fathom - Woodbury Getaway. We matched them by the tags players give Once Upon A Mind - A Little Too Friendly on Steam (Psychological Horror, Horror, Adventure, Casual, and Walking Simulator): closest matches first, and among equally close ones the better-known games.

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

Firewatch
Shared: Adventure · Walking Simulator · Atmospheric

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

SOMA
Shared: Psychological Horror · Horror · Atmospheric

Fears to Fathom - Woodbury Getaway
Shared: Psychological Horror · Horror · Adventure

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

Outlast
Shared: Horror · Psychological Horror · First-Person

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

Mouthwashing
Shared: Psychological Horror · Horror · Atmospheric

Fears to Fathom® - Scratch Creek
Shared: Horror · Psychological Horror · Adventure

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

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

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

Visage
Shared: Psychological Horror · Horror · Adventure

Scanner Sombre
Shared: Horror · Walking Simulator · Exploration

Blair Witch
Shared: Horror · Psychological Horror · Adventure

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

Layers of Fear 2 (2019)
Shared: Psychological Horror · Horror · Walking Simulator

The Park®
Shared: Psychological Horror · Horror · Walking Simulator

Lethal Company
Shared: Horror · Psychological Horror · First-Person

[Chillas Art] The Convenience Store
Shared: Horror · Psychological Horror · Adventure

Fears to Fathom - Carson House
Shared: Psychological Horror · Horror · Adventure

Little Nightmares II
Shared: Horror · Adventure · Psychological Horror

Little Nightmares
Shared: Horror · Adventure · Atmospheric