Games like STAR FLEET II - Krellan Commander Version 2.0
Games like STAR FLEET II - Krellan Commander Version 2.0 include Stellaris, X4: Foundations, Cosmoteer: Starship Architect & Commander, Elite Dangerous, and FTL: Faster Than Light. We matched them by the tags players give STAR FLEET II - Krellan Commander Version 2.0 on Steam (Simulation, Strategy, Exploration, Space Sim, and Immersive Sim): closest matches first, and among equally close ones the better-known games.

Stellaris
Shared: Strategy · Exploration · Simulation

X4: Foundations
Shared: Simulation · Space Sim · Exploration

Cosmoteer: Starship Architect & Commander
Shared: Strategy · 2D · Sci-fi

Elite Dangerous
Shared: Space Sim · Exploration · Simulation

FTL: Faster Than Light
Shared: Strategy · Sci-fi · Singleplayer

60 Seconds! Reatomized
Shared: Strategy · 2D · Exploration

Kerbal Space Program
Shared: Simulation · Space Sim · Exploration

Spaceflight Simulator
Shared: Simulation · Space Sim · Exploration

Door Kickers
Shared: Strategy · Simulation · 2D

X Rebirth
Shared: Simulation · Space Sim · Sci-fi

V: Rings of Saturn
Shared: Exploration · Space Sim · Sci-fi

Hearts of Iron IV
Shared: Strategy · Simulation · Singleplayer

911 Operator
Shared: Simulation · Strategy · Singleplayer

Hardspace: Shipbreaker
Shared: Simulation · Sci-fi · Strategy

Endless Sky
Shared: Simulation · 2D · Sci-fi

Mini Metro
Shared: Strategy · Simulation · Minimalist

Plague Inc: Evolved
Shared: Simulation · Strategy · Singleplayer

Oxygen Not Included
Shared: Simulation · 2D · Strategy

Men of War: Assault Squad 2
Shared: Strategy · Simulation · Real Time Tactics

EVE Online
Shared: Exploration · Space Sim · Simulation

60 Seconds!
Shared: Exploration · Immersive Sim · Strategy

Nimbatus - The Space Drone Constructor
Shared: Strategy · Space Sim · Exploration

Mini Motorways
Shared: Simulation · Strategy · Minimalist

RimWorld
Shared: Strategy · Simulation · Singleplayer