Games like Room Zero
Games like Room Zero include No, I'm not a Human, Mouthwashing, Sally Face - Episode One, The Coffin of Andy and Leyley, and Outer Wilds. We matched them by the tags players give Room Zero on Steam (Horror, Psychological, Multiple Endings, Adventure, and Story Rich): closest matches first, and among equally close ones the better-known games.

No, I'm not a Human
Shared: Horror · Story Rich · Multiple Endings

Mouthwashing
Shared: Horror · Story Rich · Psychological

Sally Face - Episode One
Shared: Horror · Story Rich · Adventure

The Coffin of Andy and Leyley
Shared: Psychological · Multiple Endings · Story Rich

Outer Wilds
Shared: Exploration · Adventure · Story Rich

SILENT HILL 2
Shared: Horror · Story Rich · Psychological

Firewatch
Shared: Adventure · Story Rich · Mystery

What Remains of Edith Finch
Shared: Story Rich · Adventure · Mystery

SOMA
Shared: Horror · Story Rich · Psychological Horror

Poppy Playtime
Shared: Horror · Mystery · Dark

Amnesia: A Machine For Pigs
Shared: Horror · Story Rich · Exploration

Fran Bow
Shared: Horror · Story Rich · Adventure

Five Nights at Freddy's: Security Breach
Shared: Horror · Multiple Endings · Exploration

The Casting of Frank Stone™
Shared: Horror · Multiple Endings · Story Rich

The Test
Shared: Multiple Endings · Story Rich · Psychological

The Cat Lady
Shared: Horror · Adventure · Story Rich

Little Nightmares II
Shared: Horror · Adventure · Story Rich

Notch - The Innocent LunA: Eclipsed SinnerS
Shared: Horror · Story Rich · Mystery

Layers of Fear (2016)
Shared: Horror · Story Rich · Psychological Horror

INDIKA
Shared: Horror · Story Rich · Psychological

Superliminal
Shared: Psychological · Story Rich · First-Person

CARIMARA: Beneath the forlorn limbs
Shared: Horror · Story Rich · Adventure

Until Dawn™
Shared: Horror · Multiple Endings · Adventure

OMORI
Shared: Story Rich · Multiple Endings · Horror