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

Phasmophobia
Shared: Horror · Online Co-Op · Multiplayer

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

Pacify
Shared: Horror · Online Co-Op · Multiplayer

Dead by Daylight
Shared: Horror · Multiplayer · Online Co-Op

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

Lethal Company
Shared: Horror · Online Co-Op · Co-op

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

Demonologist
Shared: Horror · Online Co-Op · Multiplayer

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

DEVOUR
Shared: Horror · Online Co-Op · Multiplayer

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

Labyrinthine
Shared: Horror · Online Co-Op · Multiplayer

Inside the Backrooms
Shared: Horror · Multiplayer · Psychological Horror

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

Buckshot Roulette
Shared: Multiplayer · Horror · First-Person

Left 4 Dead 2
Shared: Multiplayer · Co-op · Online Co-Op

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

BIGFOOT
Shared: Horror · Multiplayer · Online Co-Op

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

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

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

In Silence
Shared: Horror · Online Co-Op · Multiplayer

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

Ready or Not
Shared: Multiplayer · Horror · Co-op