Games like Under The Stars
Games like Under The Stars include Endless Sky, FTL: Faster Than Light, Kerbal Space Program, Cosmoteer: Starship Architect & Commander, and Cyberhunt. We matched them by the tags players give Under The Stars on Steam (Flight, 2D, Indie, Space, and Space Sim): closest matches first, and among equally close ones the better-known games.

Endless Sky
Shared: Space · 2D · Simulation

FTL: Faster Than Light
Shared: Space · Indie · Singleplayer

Kerbal Space Program
Shared: Space · Space Sim · Indie

Cosmoteer: Starship Architect & Commander
Shared: 2D · Space · Indie

Cyberhunt
Shared: Indie · 2D · Casual

Chorus
Shared: Indie · Space · Flight

Solar 2
Shared: Indie · Space · 2D

Melvor Idle
Shared: Indie · 2D · Casual

EVERSPACE™
Shared: Space · Indie · Flight

STAR WARS™: Squadrons
Shared: Flight · Space · Singleplayer

House of the Dying Sun
Shared: Indie · Space · Flight

Spaceflight Simulator
Shared: Space · 2D · Space Sim

Vampire Survivors
Shared: 2D · Indie · Casual

Ostranauts
Shared: Flight · Space Sim · Space

Starcom: Unknown Space
Shared: Space · Space Sim · Indie

Reassembly
Shared: Space · 2D · Indie

SpaceBourne 2
Shared: Flight · Space Sim · Space

Game Dev Tycoon
Shared: Indie · 2D · Casual

Rebel Galaxy
Shared: Space · Space Sim · Indie

Trailmakers
Shared: Space · Flight · Indie

Exo One
Shared: Flight · Space · Space Sim

Heat Signature
Shared: Space · Indie · Top-Down

LUFTRAUSERS
Shared: Indie · 2D · Flight

12 is Better Than 6
Shared: Shooter · Indie · 2D