Games like Smile and Play
Games like Smile and Play include Firewatch, MiSide, What Remains of Edith Finch, Layers of Fear (2016), and Mouthwashing. We matched them by the tags players give Smile and Play on Steam (Singleplayer, Walking Simulator, 3D, Realistic, and Atmospheric): closest matches first, and among equally close ones the better-known games.

Firewatch
Shared: Walking Simulator · Atmospheric · Singleplayer

MiSide
Shared: Singleplayer · Story Rich · Horror

What Remains of Edith Finch
Shared: Walking Simulator · Atmospheric · Story Rich

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

Mouthwashing
Shared: Horror · Atmospheric · Story Rich

The Beginner's Guide
Shared: Walking Simulator · Singleplayer · Story Rich

Hellblade: Senua's Sacrifice
Shared: Atmospheric · Singleplayer · Story Rich

Little Nightmares
Shared: Singleplayer · Atmospheric · Horror

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

DEATH STRANDING DIRECTOR'S CUT
Shared: Walking Simulator · Story Rich · Atmospheric

INSIDE
Shared: Atmospheric · Singleplayer · Horror

No, I'm not a Human
Shared: Singleplayer · Horror · Atmospheric

Welcome to Kowloon
Shared: Walking Simulator · Atmospheric · Horror

SOMA
Shared: Horror · Atmospheric · Story Rich

Garten of Banban
Shared: Singleplayer · Horror · 3D

Little Nightmares II
Shared: Singleplayer · Horror · Atmospheric

Zoochosis
Shared: 3D · Realistic · Singleplayer

Subliminal
Shared: Singleplayer · Realistic · Atmospheric

Five Nights at Freddy's: Security Breach
Shared: Singleplayer · Horror · 3D

POOLS
Shared: Walking Simulator · Realistic · Atmospheric

Red Dead Redemption 2
Shared: Story Rich · Singleplayer · Realistic

Visage
Shared: Horror · Singleplayer · Atmospheric

Copycat
Shared: Singleplayer · Indie · Walking Simulator

Ready or Not
Shared: Realistic · Singleplayer · Horror