Games like Umbral
Games like Umbral include What Remains of Edith Finch, Firewatch, Sally Face - Episode One, Mouthwashing, and Layers of Fear (2016). We matched them by the tags players give Umbral on Steam (Story Rich, Walking Simulator, Psychological Horror, Mystery, and Realistic): closest matches first, and among equally close ones the better-known games.

What Remains of Edith Finch
Shared: Story Rich · Walking Simulator · Mystery

Firewatch
Shared: Story Rich · Walking Simulator · Mystery

Sally Face - Episode One
Shared: Story Rich · Psychological Horror · Dark

Mouthwashing
Shared: Story Rich · Psychological Horror · Walking Simulator

Layers of Fear (2016)
Shared: Psychological Horror · Walking Simulator · Story Rich

Amnesia: A Machine For Pigs
Shared: Walking Simulator · Story Rich · Psychological Horror

SOMA
Shared: Psychological Horror · Story Rich · Dark

The Beginner's Guide
Shared: Story Rich · Walking Simulator · Atmospheric

Hellblade: Senua's Sacrifice
Shared: Story Rich · Atmospheric · Dark

No, I'm not a Human
Shared: Psychological Horror · Story Rich · Dark

Still Wakes the Deep
Shared: Psychological Horror · Walking Simulator · Story Rich

Fran Bow
Shared: Story Rich · Psychological Horror · Dark

Luto
Shared: Walking Simulator · Story Rich · Psychological Horror

Oxenfree
Shared: Story Rich · Mystery · Supernatural

DON'T SCREAM
Shared: Psychological Horror · Walking Simulator · Mystery

Little Nightmares II
Shared: Story Rich · Psychological Horror · Dark

The Suicide of Rachel Foster
Shared: Walking Simulator · Mystery · Story Rich

Outer Wilds
Shared: Story Rich · Mystery · Atmospheric

God's Basement
Shared: Psychological Horror · Walking Simulator · Story Rich

Visage
Shared: Psychological Horror · Dark · Walking Simulator

Poppy Playtime
Shared: Psychological Horror · Dark · Mystery

MiSide
Shared: Story Rich · Psychological Horror · Atmospheric

Hellblade II: Senua’s Saga
Shared: Story Rich · Psychological Horror · Dark

The Vanishing of Ethan Carter
Shared: Mystery · Walking Simulator · Story Rich