What are some alternatives?
When comparing Galaxy on Fire and Empyrion, you can also consider the following products
EVE Online - Player-created empires, player-driven markets, and endless ways to embark on your personal sci-fi adventure.
StarMade - StarMade is a Minecraft inspired 3D space shooter.
OGame - OGame is an addictive, Massively Multiplayer Online, Real-time Strategy, Space-war, and Money Management Browser-based video game develop by Gameforge AG.
Vendetta Online - The space-based MMO Vendetta Online balances an online trading system with tense ship-to=ship combat.
Avorion - Explore, build, fight, trad and mine in a procedural co-op space sandbox.
Evochron Mercenary - Official Webpage for Evochron Mercenary, a 3D space combat and trader simulation. Screenshots, free demo, forum, cheats, videos, and more.