Games like Backrooms: Exploration
Games like Backrooms: Exploration include Layers of Fear (2016), Firewatch, SOMA, What Remains of Edith Finch, and Outlast. We matched them by the tags players give Backrooms: Exploration on Steam (Horror, Adventure, First-Person, Realistic, and Story Rich): closest matches first, and among equally close ones the better-known games.

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

Firewatch
Shared: Adventure · Story Rich · First-Person

SOMA
Shared: Horror · Psychological Horror · Story Rich

What Remains of Edith Finch
Shared: Story Rich · First-Person · Adventure

Outlast
Shared: Horror · First-Person · Psychological Horror

Visage
Shared: Horror · Psychological Horror · First-Person

Little Nightmares II
Shared: Horror · Adventure · Singleplayer

MiSide
Shared: Horror · Psychological Horror · Story Rich

Amnesia: A Machine For Pigs
Shared: Horror · First-Person · Story Rich

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

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

Poppy Playtime
Shared: Horror · First-Person · Singleplayer

Little Nightmares
Shared: Horror · Adventure · Singleplayer

Blair Witch
Shared: Horror · Adventure · First-Person

Phasmophobia
Shared: Horror · Psychological Horror · First-Person

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

Mouthwashing
Shared: Horror · Psychological Horror · Story Rich

The Beast Inside
Shared: Horror · Adventure · First-Person

Welcome to Kowloon
Shared: Horror · Adventure · First-Person

Backrooms: Escape Together
Shared: Horror · Psychological Horror · First-Person

Escape the Backrooms
Shared: Horror · Psychological Horror · First-Person

Ready or Not
Shared: Realistic · Horror · First-Person

Five Nights at Freddy's: Security Breach
Shared: Horror · First-Person · Singleplayer

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