Games like First Floor
Games like First Floor include The Room, Firewatch, Poppy Playtime, Garten of Banban, and MiSide. We matched them by the tags players give First Floor on Steam (Casual, First-Person, Singleplayer, Horror, and 3D): closest matches first, and among equally close ones the better-known games.

The Room
Shared: Singleplayer · Mystery · Atmospheric

Firewatch
Shared: First-Person · Singleplayer · Mystery

Poppy Playtime
Shared: Singleplayer · Horror · First-Person

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

MiSide
Shared: First-Person · Horror · Singleplayer

The Room Two
Shared: Mystery · Horror · Singleplayer

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

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

Outlast
Shared: First-Person · Horror · Singleplayer

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

Garten of Banban 2
Shared: First-Person · Singleplayer · Horror

Bendy and the Ink Machine
Shared: First-Person · Horror · Singleplayer

The Room 4: Old Sins
Shared: Mystery · Singleplayer · Horror

Fears to Fathom - Woodbury Getaway
Shared: First-Person · Casual · Horror

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

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

Garten of Banban 3
Shared: First-Person · Singleplayer · Horror

Buckshot Roulette
Shared: First-Person · Horror · Singleplayer

The Death | Thần Trùng
Shared: Horror · Casual · First-Person

The Room Three
Shared: Mystery · Singleplayer · Atmospheric

The Mortuary Assistant
Shared: Horror · Singleplayer · Mystery

Resident Evil 7 Biohazard
Shared: First-Person · Horror · Singleplayer

Firework
Shared: Horror · Mystery · Singleplayer

The Hat Man: Shadow Ward
Shared: First-Person · Horror · Singleplayer