ScrumbleShip is the most accurate space combat simulation devised to date. Gather resources, construct a capital ship out of individual blocks, then pilot it with AI or human help against other players.
This image is released on a CC-BY-ND 3.0 license
And here's what happens when you let ScrumbleShippers loose on a server for a day. As you can see, they spawned (And I lit, grumble grumble) several dozen larger asteroids. Tiny blue asteroids can be seen speckling the view, and several ships and asteroid bases are visible. Easily over a half million blocks, broken up into ~60 ships and compressed into 2.4mb!
Cheers,
-Dirk
Very impressive compression there :)