Pick your race, travel to different planets, and then explore at your own pace. There are monsters to fight, items to create, and after that you’re pretty much left to your own devices. What to build a giant castle? Sure you can do that. You can go on dungeon crawls and find all sorts of treasure too. Take on giant boss fights? They’re in there! What you do in the game is really up to you.
Don’t just listen to me though. Check out the trailer that was released last week. You can see exactly what the game is capable of. I’m sure I’ll be spending some time on Starbound soon. If you do get into the game, remember it is in Beta. A lot of the streams of it I’ve seen have had random crashes in it, but that’s pretty much what Beta is for.