Games like Nostalgia
Games like Nostalgia include Phasmophobia, Escape the Backrooms, Demonologist, Inside the Backrooms, and R.E.P.O.. We matched them by the tags players give Nostalgia on Steam (Horror, First-Person, Multiplayer, Online Co-Op, and Psychological Horror): closest matches first, and among equally close ones the better-known games.

Phasmophobia
Shared: Horror · Multiplayer · Co-op

Escape the Backrooms
Shared: Horror · Multiplayer · Co-op

Demonologist
Shared: Horror · Multiplayer · Co-op

Inside the Backrooms
Shared: Horror · Multiplayer · Co-op

R.E.P.O.
Shared: Horror · Multiplayer · Co-op

DEVOUR
Shared: Horror · Multiplayer · Online Co-Op

PEAK
Shared: Co-op · Multiplayer · Online Co-Op

Lethal Company
Shared: Horror · First-Person · Co-op

Pacify
Shared: Horror · Co-op · Multiplayer

Backrooms: Escape Together
Shared: Horror · Multiplayer · Online Co-Op

The Outlast Trials
Shared: Horror · Co-op · Multiplayer

Dead by Daylight
Shared: Horror · Multiplayer · Co-op

Buckshot Roulette
Shared: Horror · Multiplayer · First-Person

RV There Yet?
Shared: Co-op · Multiplayer · Online Co-Op

How to Fish
Shared: Co-op · Multiplayer · Online Co-Op

Content Warning
Shared: Horror · Online Co-Op · Multiplayer

Labyrinthine
Shared: Horror · Co-op · Online Co-Op

Lunch Lady
Shared: Horror · Co-op · Multiplayer

Nuclear Nightmare
Shared: Horror · Co-op · Online Co-Op

Fears to Fathom® - Scratch Creek
Shared: Horror · Co-op · Multiplayer

Left 4 Dead 2
Shared: Co-op · Multiplayer · Horror

Liars Bar
Shared: Multiplayer · Co-op · Online Co-Op

PANICORE
Shared: Horror · Co-op · Online Co-Op

Outlast
Shared: Horror · First-Person · Psychological Horror