Games like Outside
Games like Outside include Outlast 2, Outlast, Resident Evil Village, Poppy Playtime, and Metro Exodus. We matched them by the tags players give Outside on Steam (Action, Indie, Horror, Violent, and First-Person): closest matches first, and among equally close ones the better-known games.

Outlast 2
Shared: Horror · First-Person · Violent

Outlast
Shared: Horror · First-Person · Survival

Resident Evil Village
Shared: Horror · Action · First-Person

Poppy Playtime
Shared: Horror · First-Person · Singleplayer

Metro Exodus
Shared: Action · Horror · Singleplayer

Resident Evil 7 Biohazard
Shared: Horror · First-Person · Singleplayer

Bendy and the Dark Revival
Shared: Horror · Action · First-Person

The Forest
Shared: Horror · Survival · Action

We Happy Few
Shared: Action · Indie · Survival

The Beast Inside
Shared: Horror · Action · First-Person

Resident Evil 4
Shared: Action · Horror · Singleplayer

Bendy and the Ink Machine
Shared: Horror · First-Person · Singleplayer

Ultimate Custom Night
Shared: Horror · Singleplayer · First-Person

METRO 2033 Redux
Shared: Action · Horror · First-Person

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

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

Five Nights at Freddy's: Sister Location
Shared: Horror · First-Person · Singleplayer

METRO Last Light Redux
Shared: Action · Horror · First-Person

Slender: The Arrival
Shared: Horror · Indie · First-Person

Five Nights at Freddy's 4
Shared: Horror · First-Person · Singleplayer

FIVE NIGHTS AT FREDDY'S: HELP WANTED
Shared: Horror · Action · First-Person

Five Nights at Freddy's 2
Shared: Horror · Indie · Singleplayer

Blair Witch
Shared: Horror · Indie · First-Person

The Outlast Trials
Shared: Horror · First-Person · Action