Looks interesting. In what sense is it supposed to be sandbox? From what I read on the blog the current version consists of a few missions. Is their eventually going to be open world play in the style of Space Rangers 2 or Freelancer?
They're aiming to provide an open universe where you can interact with different planets and groups of people. You'll be able to upgrade your ship, build up a fleet, trade and more.
The alpha just contains some combat that they've organized into missions because they've been working primarily on just the combat so far.