Neat, module-based ship construction and exploration sim that features procedurally-generated galaxies to explore and a lot of different modes to suit many tastes. I really love the Steam Workshop integration as well. All in all, it gets my thumbs up.
For a more hands-on look at the game, check out my first impressions It Didn't Play Itself session, as broken into three episodes starting here: https://www.youtube.com/watch?v=CLTziP3KbJ4
Full disclosure: I was approached via email with an offer for a key for this game, unsolicited. All of the custom ships besides those packed in with the game came from Steam Workshop creators and in no way are my work.