Games like Hourglass
Games like Hourglass include Portal, Portal 2, What Remains of Edith Finch, Viewfinder, and The Witness. We matched them by the tags players give Hourglass on Steam (Puzzle, Puzzle Platformer, First-Person, Atmospheric, and Adventure): closest matches first, and among equally close ones the better-known games.

Portal
Shared: Puzzle · Puzzle Platformer · First-Person

Portal 2
Shared: Puzzle · First-Person · Puzzle Platformer

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

Viewfinder
Shared: Puzzle · Puzzle Platformer · First-Person

The Witness
Shared: Puzzle · First-Person · Exploration

COCOON
Shared: Puzzle · Adventure · Puzzle Platformer

LIMBO
Shared: Puzzle Platformer · Puzzle · Atmospheric

Supraland
Shared: Puzzle Platformer · First-Person · Adventure

Outer Wilds
Shared: Puzzle · Adventure · Exploration

The Talos Principle
Shared: Puzzle · First-Person · Atmospheric

Little Nightmares
Shared: Atmospheric · Puzzle Platformer · Adventure

Firewatch
Shared: Atmospheric · Adventure · First-Person

Antichamber
Shared: Puzzle · First-Person · Adventure

GRIS
Shared: Atmospheric · Adventure · Female Protagonist

Call of the Sea
Shared: Puzzle · Adventure · First-Person

The Last Campfire
Shared: Puzzle · Adventure · Atmospheric

Planet of Lana
Shared: Puzzle Platformer · Puzzle · Atmospheric

Blue Prince
Shared: Puzzle · First-Person · Exploration

The Room
Shared: Puzzle · Atmospheric · Adventure

Return of the Obra Dinn
Shared: Puzzle · Atmospheric · First-Person

FAR: Lone Sails
Shared: Atmospheric · Adventure · Puzzle

A Story About My Uncle
Shared: First-Person · Adventure · Atmospheric

Stray
Shared: Atmospheric · Adventure · Puzzle

Chants of Sennaar
Shared: Puzzle · Adventure · Atmospheric