Basically, oh my GOD! Billion-star procedurally-generated galaxy in a persistent online world to explore as you wish, with NO loading screens or transitions, just straight flight down to the planet. I can't even begin to describe how cool this game is and *glurgle* the graphics...
http://www.infinity-universe.com/Seriously, check the renders and other media. They made my belly fizz.
EDIT: Also, Newtonian physics ftw
EDIT2: Also also, check Youtube for more amazing videos, including this beast:
Flamberge FlybyYes, that's in-game footage of an incredibly large ship flying through the clouds of a random, precedurally-generated world orbiting a procedurally generated sun in a procedurally generated solar system...
Infinity - Procedural real-time galaxy modelInfinity Starfield VideoYes, you can go anywhere in that.
Planet and Ring VideoYes, that was generated on the fly.
GHEEEEEEEEEEEEE