Games like Project 17
Games like Project 17 include Firewatch, What Remains of Edith Finch, Amnesia: A Machine For Pigs, Escape the Backrooms, and Inside the Backrooms. We matched them by the tags players give Project 17 on Steam (Adventure, Action-Adventure, Walking Simulator, Exploration, and FPS): closest matches first, and among equally close ones the better-known games.

Firewatch
Shared: Adventure · Walking Simulator · Atmospheric

What Remains of Edith Finch
Shared: Walking Simulator · Adventure · Exploration

Amnesia: A Machine For Pigs
Shared: Walking Simulator · Horror · Exploration

Escape the Backrooms
Shared: Horror · Adventure · Exploration

Inside the Backrooms
Shared: Adventure · Horror · Exploration

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

Far Cry® 5
Shared: Action-Adventure · FPS · Exploration

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

SILENT HILL: Townfall
Shared: Adventure · Action-Adventure · Horror

Resident Evil Requiem
Shared: FPS · Action-Adventure · Horror

SOMA
Shared: Horror · Atmospheric · Exploration

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

Layers of Fear (2016)
Shared: Walking Simulator · Adventure · Horror

Outer Wilds
Shared: Exploration · Adventure · Mystery

Lethal Company
Shared: First-Person · Exploration · Horror

Metro Exodus
Shared: FPS · Atmospheric · Adventure

Outlast
Shared: First-Person · Horror · Atmospheric

Scanner Sombre
Shared: Walking Simulator · Exploration · Adventure

DREDGE
Shared: Exploration · Adventure · Atmospheric

METRO 2033 Redux
Shared: FPS · Atmospheric · Horror

Hello Neighbor
Shared: First-Person · Action-Adventure · Horror

Atomic Heart
Shared: Adventure · FPS · Action-Adventure

INFRA
Shared: Exploration · Adventure · Walking Simulator

Choo-Choo Charles
Shared: First-Person · Horror · Action-Adventure