Games like DeathStairwell99F
Games like DeathStairwell99F include Five Nights at Freddy's: Security Breach, Firewatch, Slime Rancher, Escape the Backrooms, and Poppy Playtime. We matched them by the tags players give DeathStairwell99F on Steam (Singleplayer, Adventure, Horror, First-Person, and Exploration): closest matches first, and among equally close ones the better-known games.

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

Firewatch
Shared: Adventure · Singleplayer · First-Person

Slime Rancher
Shared: Adventure · Singleplayer · Exploration

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

Poppy Playtime
Shared: Singleplayer · Horror · First-Person

Fallout 4
Shared: Singleplayer · Adventure · Exploration

Outlast
Shared: Horror · First-Person · Singleplayer

The Forest
Shared: Horror · Adventure · First-Person

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

Scanner Sombre
Shared: Horror · Exploration · Adventure

The Elder Scrolls IV: Oblivion Remastered
Shared: Singleplayer · Adventure · RPG

Subnautica
Shared: Horror · Singleplayer · Exploration

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

MiSide
Shared: Horror · Singleplayer · First-Person

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

Fallout: New Vegas
Shared: Singleplayer · RPG · Exploration

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

Starfield
Shared: Singleplayer · Exploration · First-Person

Bendy and the Dark Revival
Shared: Singleplayer · Horror · First-Person

Tainted Grail: The Fall of Avalon
Shared: Adventure · First-Person · Singleplayer

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

Subnautica: Below Zero
Shared: Singleplayer · Horror · Exploration

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

Fears to Fathom - Ironbark Lookout
Shared: Horror · Adventure · Exploration