Games like 20 Floors
Games like 20 Floors include Firewatch, What Remains of Edith Finch, Escape the Backrooms, The Exit 8, and Amnesia: A Machine For Pigs. We matched them by the tags players give 20 Floors on Steam (Adventure, Walking Simulator, Action-Adventure, Exploration, and First-Person): closest matches first, and among equally close ones the better-known games.

Firewatch
Shared: Adventure · Walking Simulator · First-Person

What Remains of Edith Finch
Shared: Walking Simulator · Adventure · First-Person

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

The Exit 8
Shared: Walking Simulator · Exploration · Horror

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

POOLS
Shared: Walking Simulator · Exploration · First-Person

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

PEAK
Shared: Adventure · Exploration · First-Person

Poppy Playtime
Shared: Horror · First-Person · Adventure

Amnesia: Rebirth
Shared: Action-Adventure · First-Person · Adventure

Platform 8
Shared: Adventure · Walking Simulator · Exploration

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

Bad Parenting 1: Mr. Red Face
Shared: Adventure · Walking Simulator · Horror

The Cabin Factory
Shared: Walking Simulator · Adventure · Horror

Visage
Shared: Horror · Adventure · First-Person

Psalm 5:9-13
Shared: Exploration · Walking Simulator · Horror

Five Nights at Freddy's: Secret of the Mimic
Shared: Adventure · First-Person · Horror

SILENT HILL: Townfall
Shared: Adventure · Horror · First-Person

CARIMARA: Beneath the forlorn limbs
Shared: Adventure · Exploration · Walking Simulator

Still Wakes the Deep
Shared: Walking Simulator · Horror · First-Person

SOMA
Shared: Horror · Exploration · Psychological Horror

Scanner Sombre
Shared: Walking Simulator · Exploration · Adventure

Amenti
Shared: Adventure · Exploration · Walking Simulator

The Inn-Sanity
Shared: Adventure · Walking Simulator · Horror