Games like Psychotic Nightmare
Games like Psychotic Nightmare include Poppy Playtime, Blue Prince, MiSide, Little Nightmares II, and Superliminal. We matched them by the tags players give Psychotic Nightmare on Steam (Psychological Horror, Singleplayer, Puzzle, Investigation, and Exploration): closest matches first, and among equally close ones the better-known games.

Poppy Playtime
Shared: Singleplayer · Puzzle · Psychological Horror

Blue Prince
Shared: Puzzle · Investigation · Exploration

MiSide
Shared: Psychological Horror · Singleplayer · First-Person

Little Nightmares II
Shared: Singleplayer · Puzzle · Adventure

Superliminal
Shared: Puzzle · Singleplayer · First-Person

Indiana Jones and the Great Circle
Shared: Puzzle · Singleplayer · First-Person

Amnesia: Rebirth
Shared: Puzzle · Singleplayer · First-Person

Outer Wilds
Shared: Exploration · Adventure · Puzzle

What Remains of Edith Finch
Shared: Singleplayer · Exploration · First-Person

Fran Bow
Shared: Psychological Horror · Puzzle · Singleplayer

SOMA
Shared: Psychological Horror · Exploration · Singleplayer

Little Nightmares
Shared: Singleplayer · Adventure · Puzzle

Sally Face - Episode One
Shared: Psychological Horror · Puzzle · Indie

ROUTINE
Shared: Singleplayer · Psychological Horror · Puzzle

Five Nights at Freddy's: Security Breach
Shared: Singleplayer · First-Person · Exploration

Portal 2
Shared: Singleplayer · Puzzle · First-Person

Layers of Fear (2016)
Shared: Psychological Horror · Singleplayer · First-Person

Garten of Banban
Shared: Singleplayer · Psychological Horror · Puzzle

Buckshot Roulette
Shared: Singleplayer · First-Person · Psychological Horror

Escape the Backrooms
Shared: Psychological Horror · First-Person · Exploration

Firewatch
Shared: Adventure · Singleplayer · First-Person

Antichamber
Shared: Puzzle · Singleplayer · First-Person

Riven
Shared: Puzzle · Singleplayer · Exploration

Inside the Backrooms
Shared: Psychological Horror · Puzzle · Adventure