Starforge type gameplay

Hey guys!
Most of you must know the game called StarForge (developed in unity) if not heres a link:

Now what im interested in, and this is more of a open question, is how can unity support a map of that scale (a whole planet and reaching out into space) and how can I make a similar building mode, where blocks snap to each others grid and their textures “combine”
Im not asking for a script, im just asking for suggestions as ive never been able to make blocks snap to a terrain and each other this way.

BTW ( Does anyone have a clue if this is photon/unity/smartfox?)

Thanks

I’m pretty sure thar they have unity pro, so its not supprising that it can handle a massive terrain,not to mention its proceeduarily generarated. Ithink that they used some sort of grid function in the unity engine (I’m not sure) but it would seem that codehatch has had ample training with programming. Those are just my ideas