Games like {Undefined}
Games like {Undefined} include Satisfactory, Factorio, The Forest, The Last Caretaker, and 7 Days to Die. We matched them by the tags players give {Undefined} on Steam (Exploration, Sandbox, Space Sim, Base Building, and Strategy): closest matches first, and among equally close ones the better-known games.

Satisfactory
Shared: Base Building · Sandbox · Exploration

Factorio
Shared: Sandbox · Base Building · Strategy

The Forest
Shared: Open World · Exploration · First-Person

The Last Caretaker
Shared: Base Building · Sandbox · Exploration

7 Days to Die
Shared: Base Building · Open World · Exploration

The Long Dark
Shared: Exploration · Open World · First-Person

Sons Of The Forest
Shared: Base Building · Open World · Exploration

Once Human
Shared: Exploration · Open World · Base Building

Stormworks: Build and Rescue
Shared: Sandbox · Base Building · Open World

Scrap Mechanic
Shared: Sandbox · Base Building · Open World

No Man's Sky
Shared: Exploration · Open World · Sandbox

Raft
Shared: Base Building · Sandbox · Open World

Terraria
Shared: Sandbox · Exploration · Survival

ASTRONEER
Shared: Exploration · Base Building · Sandbox

Valheim
Shared: Exploration · Base Building · Open World

Dyson Sphere Program
Shared: Base Building · Sandbox · Automation

Space Engineers
Shared: Sandbox · Base Building · Building

Rust
Shared: Sandbox · Open World · First-Person

Subnautica
Shared: Exploration · Base Building · Open World

ARK: Survival Evolved
Shared: Base Building · Open World · Sandbox

The Planet Crafter
Shared: Base Building · Exploration · Sandbox

Core Keeper
Shared: Exploration · Sandbox · Open World

Sandustry
Shared: Sandbox · Exploration · Open World

Empyrion - Galactic Survival
Shared: Exploration · Space Sim · Sandbox

