Star Trek Online - Star Trek Online (STO) is a free to play MMORPG that takes place inside the Star Trek world.
X3: Terran Conflict - X3: Terran Conflict is part of the X number of video games.
Kerbal Space Program - Build spacecraft, fly them, and try to help the Kerbals to fulfill their ultimate mission of conquering space.
EVE Online - Player-created empires, player-driven markets, and endless ways to embark on your personal sci-fi adventure.
Ace Online - Ace Online is a distinctive 3D MMO that places you in the pilot seat of your personal fighter ship (called a Gear).
FTL: Faster Than Light - FTL is a spaceship simulation roguelike-like.