Games like UNIT 44
Games like UNIT 44 include Poppy Playtime, No, I'm not a Human, Outlast, The Test, and Layers of Fear (2016). We matched them by the tags players give UNIT 44 on Steam (Psychological Horror, Horror, Simulation, First-Person, and Adventure): closest matches first, and among equally close ones the better-known games.

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

No, I'm not a Human
Shared: Psychological Horror · Horror · First-Person

Outlast
Shared: Horror · First-Person · Psychological Horror

The Test
Shared: Simulation · Psychological Horror · Pixel Graphics

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

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

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

SOMA
Shared: Psychological Horror · Horror · Atmospheric

Mouthwashing
Shared: Psychological Horror · Horror · Atmospheric

Five Nights at Freddy's
Shared: Horror · Psychological Horror · First-Person

MiSide
Shared: Psychological Horror · Horror · First-Person

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

Little Nightmares II
Shared: Horror · Adventure · Psychological Horror

Buckshot Roulette
Shared: Horror · Dark · First-Person

Iron Lung
Shared: Horror · Psychological Horror · Atmospheric

Little Nightmares
Shared: Horror · Adventure · Atmospheric

Visage
Shared: Psychological Horror · Horror · First-Person

IMSCARED
Shared: Horror · Psychological Horror · First-Person

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

Blair Witch
Shared: Horror · Psychological Horror · Adventure

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

Phasmophobia
Shared: Horror · Psychological Horror · First-Person

Firewatch
Shared: Adventure · First-Person · Atmospheric

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