Avorion is a sci-fi sandbox space game where you explore a galaxy far away from the milky way. Build your own space ship, space station, mine asteroids, and meet other players who are doing the same. Buy and sell with players online or with NPCs.
The game is features voxel based graphics, plenty of customization options, smooth controls, and great combat mechanics. There are a few voxel based space games in development now, but Avorion is certainly one of the best and well worth giving a go. With a bit of work you should be able to build a deathstar with some properly secured Jedi-proof thermal exhaust ports.