Games like Second Galaxy
Games like Second Galaxy include Star Trek Online, Warframe, Albion Online, Destiny 2, and Once Human. We matched them by the tags players give Second Galaxy on Steam (Free to Play, Massively Multiplayer, RPG, Space, and Strategy): closest matches first, and among equally close ones the better-known games.

Star Trek Online
Shared: Free to Play · Massively Multiplayer · Space

Warframe
Shared: Free to Play · RPG · Massively Multiplayer

Albion Online
Shared: Free to Play · Massively Multiplayer · RPG

Destiny 2
Shared: Free to Play · Open World · Massively Multiplayer

Once Human
Shared: Free to Play · Open World · Massively Multiplayer

Neverwinter
Shared: Free to Play · RPG · Massively Multiplayer

Endless Sky
Shared: Free to Play · Space · Open World

Where Winds Meet
Shared: Free to Play · Open World · Massively Multiplayer

Starfield
Shared: Space · RPG · Open World

Elite Dangerous
Shared: Space · Open World · Massively Multiplayer

Phantasy Star Online 2 New Genesis
Shared: Free to Play · Massively Multiplayer · Open World

Game of Thrones Winter is Coming
Shared: Free to Play · Massively Multiplayer · RPG

Marvel Rivals
Shared: Free to Play · Massively Multiplayer · RPG

Space Rangers HD: A War Apart
Shared: RPG · Space · Strategy

Starpoint Gemini Warlords
Shared: RPG · Space · Strategy

Halo Infinite
Shared: Free to Play · Open World · Sci-fi

Guild Wars 2®
Shared: Free to Play · RPG · Massively Multiplayer

Trove
Shared: Free to Play · Open World · RPG

Mortal Online
Shared: Free to Play · Massively Multiplayer · RPG

Blue Protocol: Star Resonance
Shared: Free to Play · RPG · Massively Multiplayer

EVE Online
Shared: Open World · Space · Massively Multiplayer

Wuthering Waves
Shared: Free to Play · Open World · RPG

Mount & Blade II: Bannerlord
Shared: RPG · Strategy · Open World

GWENT: The Witcher Card Game
Shared: Free to Play · RPG · Strategy