Games like Only If
Games like Only If include Poppy Playtime, Dark Deception, Firewatch, Outlast, and The Forest. We matched them by the tags players give Only If on Steam (Free to Play, Adventure, First-Person, Horror, and Puzzle): closest matches first, and among equally close ones the better-known games.

Poppy Playtime
Shared: Free to Play · Horror · First-Person

Dark Deception
Shared: Free to Play · Horror · First-Person

Firewatch
Shared: Adventure · First-Person · Walking Simulator

Outlast
Shared: First-Person · Horror · Singleplayer

The Forest
Shared: Horror · Adventure · Survival

Sons Of The Forest
Shared: Survival · Horror · First-Person

Ultimate Custom Night
Shared: Free to Play · Horror · Singleplayer

Halo Infinite
Shared: Free to Play · First-Person · Singleplayer

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

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

Samsara Room
Shared: Adventure · Free to Play · Puzzle

Subnautica
Shared: Horror · Survival · Adventure

We Were Here
Shared: Free to Play · Puzzle · Horror

Apex Legends™
Shared: Free to Play · First-Person · Multiplayer

Where Winds Meet
Shared: Free to Play · Singleplayer · Adventure

Once Human
Shared: Free to Play · Survival · Multiplayer

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

The Long Dark
Shared: First-Person · Adventure · Survival

Little Nightmares II
Shared: Adventure · Horror · Puzzle

Subnautica: Below Zero
Shared: Horror · Singleplayer · Survival

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

Granny
Shared: Horror · First-Person · Puzzle

Slender: The Arrival
Shared: Horror · First-Person · Indie

Subnautica 2
Shared: Horror · Survival · First-Person