Games like FoMO
Games like FoMO include Mouthwashing, Little Nightmares II, Outlast, Layers of Fear (2016), and FAITH: The Unholy Trinity. We matched them by the tags players give FoMO on Steam (Psychological Horror, Retro, Pixel Graphics, Adventure, and Dark): closest matches first, and among equally close ones the better-known games.

Mouthwashing
Shared: Psychological Horror · Retro · Dark

Little Nightmares II
Shared: Adventure · Psychological Horror · Dark

Outlast
Shared: Psychological Horror · First-Person · Dark

Layers of Fear (2016)
Shared: Psychological Horror · First-Person · Adventure

FAITH: The Unholy Trinity
Shared: Psychological Horror · Pixel Graphics · Retro

IMSCARED
Shared: Psychological Horror · Pixel Graphics · Adventure

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

MiSide
Shared: Psychological Horror · First-Person · Singleplayer

What Remains of Edith Finch
Shared: First-Person · Adventure · Psychological Horror

SOMA
Shared: Psychological Horror · Dark · First-Person

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

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

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

Visage
Shared: Psychological Horror · Dark · First-Person

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

DISTRAINT: Deluxe Edition
Shared: Psychological Horror · Pixel Graphics · Adventure

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

Firewatch
Shared: Adventure · First-Person · Walking Simulator

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

No one lives under the lighthouse Director's cut
Shared: Adventure · Psychological Horror · Retro

Little Nightmares
Shared: Adventure · Dark · Psychological Horror

ROUTINE
Shared: Psychological Horror · Dark · Adventure

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

Last Report
Shared: Psychological Horror · Pixel Graphics · Dark