Games like The Alters
Games like The Alters include Oxygen Not Included, RimWorld, Factorio, This War of Mine, and Subnautica. We matched them by the tags players give The Alters on Steam (Survival, Base Building, Management, Sci-fi, and Exploration): closest matches first, and among equally close ones the better-known games.

Oxygen Not Included
Shared: Base Building · Survival · Management

RimWorld
Shared: Base Building · Survival · Management

Factorio
Shared: Base Building · Survival · Resource Management

This War of Mine
Shared: Survival · Base Building · Strategy

Subnautica
Shared: Survival · Exploration · Base Building

Dune: Awakening
Shared: Survival · Base Building · Exploration

The Last Caretaker
Shared: Survival · Base Building · Crafting

Space Haven
Shared: Base Building · Survival · Management

No Man's Sky
Shared: Survival · Sci-fi · Exploration

The Planet Crafter
Shared: Base Building · Survival · Exploration

ASTRONEER
Shared: Survival · Base Building · Exploration

Satisfactory
Shared: Base Building · Crafting · Exploration

Frostpunk
Shared: Survival · Strategy · Resource Management

Dyson Sphere Program
Shared: Base Building · Sci-fi · Management

Abiotic Factor
Shared: Survival · Base Building · Sci-fi

Sons Of The Forest
Shared: Survival · Base Building · Exploration

Subnautica: Below Zero
Shared: Survival · Base Building · Exploration

Rise of the Tomb Raider™
Shared: Exploration · Survival · Singleplayer

IXION
Shared: Survival · Strategy · Base Building

Stranded: Alien Dawn
Shared: Survival · Base Building · Strategy

Valheim
Shared: Survival · Base Building · Exploration

STAR WARS Jedi: Survivor™
Shared: Sci-fi · Singleplayer · Action-Adventure

Breathedge
Shared: Survival · Base Building · Sci-fi

Enshrouded
Shared: Survival · Base Building · Exploration