I already beat the a robot BOSS and?

I'm beat a robot boss. so that means main mission is done?

 

Yes. You can still do all of the side-quests if you haven't by now. They let you upgrade your ship and unlock new techs. Also, you can keep exploring now and go to the highest planet tiers.
After that, the only thing you have to do left is building colonies, exploring for collecting codex/critters/vanity items, building cool things... you know. Or you could replay the game with another race and using another kind of weapons.
But yeah, main mission is done.

 

OPS!
The endless universe! It's my way!
Thanks! Thalant.

 

Well, "done" in that the game isn't finished being made, there's a load of story missions in-development coming in the next(?) big update, so...

 

The main mission isn't in the game yet!

 

I was surprised that the mission quests ended at that point as well. I thought I would have at least got to see the bone dragon again. I was eager to see how they made that into a real boss fight. As it stands though, the new erchius crystal boss and the bug in the floran dungeon were both very good compared to what they had in the koala builds

 

If you haven't already taken a look at it I can wholly recommend http://community.playstarbound.com/resources/frackinuniverse.2920/.

Adds a lot of depth to progression as well as having a very satisfying mission attached.