I was playing around with the in-game map generator and I got to about 20 solar systems and about 280 planets before I got bored.

Is there a limit?  I know that 10 players is the maximum, even if you have 20-something player starts.

I want to play an big epic game with lots of solar systems now.

Maybe not quite 20, but fighting over a single solar system seems kind of small to me.  Maybe I'm just used to Eve with its 5000-some-odd solar systems.