Games like Iron Lung
Games like Iron Lung include SOMA, Lethal Company, Outlast, Layers of Fear (2016), and MiSide. We matched them by the tags players give Iron Lung on Steam (Horror, Atmospheric, Psychological Horror, Submarine, and Indie): closest matches first, and among equally close ones the better-known games.

SOMA
Shared: Horror · Atmospheric · Psychological Horror

Lethal Company
Shared: Horror · Psychological Horror · First-Person

Outlast
Shared: Horror · Atmospheric · Psychological Horror

Layers of Fear (2016)
Shared: Horror · Atmospheric · Psychological Horror

MiSide
Shared: Psychological Horror · Horror · Atmospheric

DISTRAINT: Deluxe Edition
Shared: Horror · Psychological Horror · Indie

Still Wakes the Deep
Shared: Horror · Psychological Horror · Atmospheric

Firewatch
Shared: Atmospheric · Adventure · Indie

Subnautica 2
Shared: Horror · Underwater · Atmospheric

Mouthwashing
Shared: Horror · Psychological Horror · Atmospheric

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

IMSCARED
Shared: Horror · Psychological Horror · Indie

Inside the Backrooms
Shared: Horror · Psychological Horror · Atmospheric

Little Nightmares
Shared: Horror · Atmospheric · Indie

OMORI
Shared: Psychological Horror · Indie · Horror

No, I'm not a Human
Shared: Horror · Psychological Horror · Indie

Poppy Playtime
Shared: Horror · Psychological Horror · First-Person

Amnesia: A Machine For Pigs
Shared: Horror · Atmospheric · Psychological Horror

[Chillas Art] The Convenience Store
Shared: Horror · Psychological Horror · Indie

Amnesia: The Dark Descent
Shared: Horror · Psychological Horror · Atmospheric

Visage
Shared: Horror · Psychological Horror · Atmospheric

Five Nights at Freddy's
Shared: Horror · Psychological Horror · Indie

FAITH: The Unholy Trinity
Shared: Horror · Psychological Horror · Indie

Backrooms: Escape Together
Shared: Horror · Psychological Horror · Atmospheric