If you're looking for a more in-depth experience, check out Osmos [2], the single-player game that probably inspired this.
[1] https://news.ycombinator.com/item?id=378475
[2] http://www.osmos-game.com/
Seems like there were no asteroids.
The "MMO" features were fake. All the other ships flying around were bots; the game ran locally on your computer. Disconnecting from the network broke the illusion, as the game continued to run normally.
If you're looking for a more in-depth experience, check out Osmos [2], the single-player game that probably inspired this.
[1] https://news.ycombinator.com/item?id=378475
[2] http://www.osmos-game.com/