As of July 22nd, 2016, Starbound has officially reached version 1.0 and is a fully-fledged release with a complete campaign and all the planned features integrated.
Chucklefish, the lovely group of dudes and dudettes who made and continue to make it, are happy to present a story of outcasts, fleeing homeworlds in spaceships with nothing to guide them, hopelessly lost in a sea of stars.
The general mechanics of Starbound are described below:
Because they're working so hard to make each planet unique, they want to give you the tools to catalog the things you find and make sure absolutely everything you find has depth in the world. Much like old school point and click adventures, absolutely every object in the world, right down to the trees and flowers, can be examined with a description.
See a weird alien tree? Examine it! Maybe you'll discover something about its use! For any explorer, sharing discoveries is important. So whilst the game is fully Multiplayer (Bring your friends along! Form an expedition!), you can also record your findings in an electronic logbook. Not only that, but each and every planet has unique Coordinates in the Universe that you can share online, so other players can check out that nasty Dungeon you found!
Exploring is wonderful, but everyone needs a place to call their own. That's why they're letting you claim an entire planet!
When you claim a planet as your new homeworld, a whole new aspect of gameplay opens up. Everything that makes a planet unique is at your command. Feel like changing the weather? Build a weather center! Don't like the terrain? Terraform it! Every aspect of the planet is under your control. Once you're happy with it, start populating it with characters you've met in your travels and take care of them! They'll have needs and desires and won't hesitate to ask for your help if they require assistance.