Games like UNBOUND
Games like UNBOUND include Poppy Playtime, Little Nightmares II, The Room, The Room 4: Old Sins, and Little Nightmares. We matched them by the tags players give UNBOUND on Steam (Horror, Adventure, Escape Room, Singleplayer, and First-Person): closest matches first, and among equally close ones the better-known games.

Poppy Playtime
Shared: Horror · Singleplayer · First-Person

Little Nightmares II
Shared: Horror · Adventure · Singleplayer

The Room
Shared: Puzzle · Adventure · Singleplayer

The Room 4: Old Sins
Shared: Adventure · Puzzle · Escape Room

Little Nightmares
Shared: Horror · Adventure · Singleplayer

Garten of Banban
Shared: Horror · Singleplayer · First-Person

The Room Three
Shared: Adventure · Puzzle · Singleplayer

MiSide
Shared: Horror · First-Person · Singleplayer

The Room Two
Shared: Horror · Puzzle · Adventure

Outer Wilds
Shared: Adventure · Mystery · Puzzle

Bendy and the Ink Machine
Shared: Horror · Singleplayer · First-Person

Firewatch
Shared: Adventure · First-Person · Singleplayer

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

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

Outlast
Shared: Horror · First-Person · Singleplayer

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

Sally Face - Episode One
Shared: Horror · Adventure · Puzzle

Garten of Banban 2
Shared: Horror · Singleplayer · First-Person

SOMA
Shared: Horror · Atmospheric · First-Person

Inside the Backrooms
Shared: Horror · Puzzle · Adventure

Blue Prince
Shared: Puzzle · Singleplayer · Adventure

Servant of the Lake
Shared: Adventure · Escape Room · Puzzle

Rusty Lake Paradise
Shared: Adventure · Horror · Puzzle

Buckshot Roulette
Shared: Horror · First-Person · Singleplayer