Games like Lethe - Episode One
Games like Lethe - Episode One include The Forest, Outlast, Poppy Playtime, Bendy and the Dark Revival, and We Happy Few. We matched them by the tags players give Lethe - Episode One on Steam (Adventure, Indie, Action, Horror, and First-Person): closest matches first, and among equally close ones the better-known games.

The Forest
Shared: Horror · Adventure · Survival

Outlast
Shared: Horror · First-Person · Atmospheric

Poppy Playtime
Shared: Horror · First-Person · Puzzle

Bendy and the Dark Revival
Shared: Horror · Action · Adventure

We Happy Few
Shared: Adventure · Action · Indie

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

The Hat Man: Shadow Ward
Shared: Indie · Adventure · Horror

Paper Dolls: Original /
Shared: Adventure · Horror · Action

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

Little Nightmares
Shared: Adventure · Horror · Atmospheric

Penumbra Overture
Shared: Adventure · Horror · Indie

Among the Sleep - Enhanced Edition
Shared: Indie · Adventure · Horror

Sons Of The Forest
Shared: Survival · Horror · Adventure

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

METRO Last Light Redux
Shared: Action · Atmospheric · Horror

Five Nights at Freddy's: Secret of the Mimic
Shared: Adventure · Horror · First-Person

Little Nightmares II
Shared: Adventure · Horror · Atmospheric

Hello Neighbor 2
Shared: Adventure · Horror · First-Person

METRO 2033 Redux
Shared: Horror · Action · Atmospheric

The Room
Shared: Adventure · Puzzle · Atmospheric

Firewatch
Shared: Adventure · Atmospheric · First-Person

Amnesia: The Dark Descent
Shared: Horror · Atmospheric · First-Person

Spooky's Jump Scare Mansion: HD Renovation
Shared: Indie · Adventure · Horror

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