Games like The Forgotten Nightmare Series
Games like The Forgotten Nightmare Series include Outer Wilds, Firewatch, What Remains of Edith Finch, Return of the Obra Dinn, and Murders on the Yangtze River. We matched them by the tags players give The Forgotten Nightmare Series on Steam (Interactive Fiction, Text-Based, Mystery, Story Rich, and Puzzle): closest matches first, and among equally close ones the better-known games.

Outer Wilds
Shared: Mystery · Story Rich · Exploration

Firewatch
Shared: Story Rich · Mystery · Adventure

What Remains of Edith Finch
Shared: Story Rich · Mystery · Atmospheric

Return of the Obra Dinn
Shared: Mystery · Story Rich · Puzzle

Murders on the Yangtze River
Shared: Puzzle · Story Rich · Mystery

Sally Face - Episode One
Shared: Story Rich · Puzzle · Mystery

To the Moon
Shared: Story Rich · Interactive Fiction · Adventure

Blue Prince
Shared: Mystery · Puzzle · Story Rich

Sanfu
Shared: Mystery · Puzzle · Adventure

FAR: Lone Sails
Shared: Post-apocalyptic · Adventure · Puzzle

The Death Game Report
Shared: Mystery · Puzzle · Story Rich

Amanda the Adventurer
Shared: Puzzle · Mystery · Story Rich

Finding Paradise
Shared: Story Rich · Interactive Fiction · Adventure

No Case Should Remain Unsolved
Shared: Interactive Fiction · Puzzle · Story Rich

Brothers - A Tale of Two Sons
Shared: Story Rich · Adventure · Puzzle

The Talos Principle
Shared: Puzzle · Story Rich · Atmospheric

The Room 4: Old Sins
Shared: Mystery · Puzzle · Story Rich

The Roottrees are Dead
Shared: Mystery · Puzzle · Story Rich

Twelve Minutes
Shared: Mystery · Story Rich · Puzzle

A Space for the Unbound
Shared: Story Rich · Puzzle · Exploration

Fallout 4
Shared: Post-apocalyptic · Story Rich · Exploration

Call of the Sea
Shared: Story Rich · Puzzle · Adventure

The Room Three
Shared: Mystery · Puzzle · Adventure

Strange Horticulture
Shared: Mystery · Puzzle · Story Rich