Games like The Line
Games like The Line include Blue Prince, Outer Wilds, Firewatch, What Remains of Edith Finch, and The Witness. We matched them by the tags players give The Line on Steam (Adventure, Puzzle, Exploration, Investigation, and First-Person): closest matches first, and among equally close ones the better-known games.

Blue Prince
Shared: Puzzle · Exploration · Investigation

Outer Wilds
Shared: Exploration · Adventure · Mystery

Firewatch
Shared: Adventure · Atmospheric · First-Person

What Remains of Edith Finch
Shared: Atmospheric · Adventure · Exploration

The Witness
Shared: Puzzle · Exploration · First-Person

Stray
Shared: Adventure · Exploration · Atmospheric

The Room
Shared: Puzzle · Adventure · Mystery

Quern - Undying Thoughts
Shared: Adventure · Puzzle · Exploration

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

Riven
Shared: Adventure · Puzzle · Exploration

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

Chants of Sennaar
Shared: Adventure · Puzzle · Indie

Antichamber
Shared: Puzzle · First-Person · Exploration

INFRA
Shared: Puzzle · Exploration · Adventure

Return of the Obra Dinn
Shared: Puzzle · Mystery · Atmospheric

Murders on the Yangtze River
Shared: Puzzle · Adventure · Exploration

Poppy Playtime
Shared: Puzzle · First-Person · Singleplayer

The Painscreek Killings
Shared: Investigation · Exploration · Puzzle

Obduction
Shared: Adventure · Puzzle · Exploration

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

FAR: Lone Sails
Shared: Adventure · Atmospheric · Exploration

The Room Two
Shared: Puzzle · Adventure · Mystery

The Room Three
Shared: Puzzle · Adventure · Mystery

The House of Da Vinci
Shared: Puzzle · Exploration · Adventure