Games like Return to Planet X
Games like Return to Planet X include The Forest, No Man's Sky, Black Mesa, Half-Life 2, and Alien: Isolation. We matched them by the tags players give Return to Planet X on Steam (Action, Indie, Adventure, First-Person, and Horror): closest matches first, and among equally close ones the better-known games.

The Forest
Shared: Horror · Survival · Adventure

No Man's Sky
Shared: Space · Survival · Adventure

Black Mesa
Shared: Action · First-Person · Sci-fi

Half-Life 2
Shared: Action · First-Person · Adventure

Alien: Isolation
Shared: Horror · First-Person · Sci-fi

Fallout 4
Shared: Adventure · First-Person · Exploration

Metro Exodus
Shared: Action · Horror · First-Person

Subnautica
Shared: Horror · Survival · Adventure

BioShock Infinite
Shared: Action · First-Person · Shooter

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

Outlast
Shared: First-Person · Horror · Survival

We Happy Few
Shared: Adventure · Action · Survival

Outer Wilds
Shared: Adventure · Space · Exploration

Lethal Company
Shared: First-Person · Horror · Exploration

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

The Long Dark
Shared: Survival · First-Person · Adventure

Deliver Us The Moon
Shared: Indie · Action · Adventure

S.T.A.L.K.E.R. 2: Heart of Chornobyl - Standard Edition
Shared: Survival · Shooter · Action

Subnautica: Below Zero
Shared: Survival · Horror · Adventure

Prey
Shared: Horror · Space · First-Person

Breathedge
Shared: Indie · Space · Survival

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

PUBG: BATTLEGROUNDS
Shared: Survival · Action · Shooter

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