What are some alternatives?
When comparing Galaxy on Fire and Avorion, 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.
Empyrion - Empyrion is a 3D open world, space survival adventure in which you can fly across space and land on...
OGame - OGame is an addictive, Massively Multiplayer Online, Real-time Strategy, Space-war, and Money Management Browser-based video game develop by Gameforge AG.
StarMade - StarMade is a Minecraft inspired 3D space shooter.
Vendetta Online - The space-based MMO Vendetta Online balances an online trading system with tense ship-to=ship combat.
Space Engineers - Space Engineers is an Action-Adventure, Sandbox, Voxel-based, Space, Single and Multiplayer video game created and published by Keen Software House.