In the demo, notice there is a negative cash flow for a few seconds called "rehabilitation fund". This can be exploited plus others that will actually make the gameplay much more fun for all.
The way the game is now, it is a "Saddle Point" situation for all you math savy folks. Once one said gets the edge, the ball rolls down hill in his favor. The winner gets extra income for the planet, plus an extra population total point, deny both form the losing side. It will snow ball quickly into a complete rush.
I think to give the losing player a chance and stop the snow ball giant fleet, make them have a maintenance cost to keep ALL units space and ground, plus undeveloped planets in hold. Thus it would take alot of money for the winning team to hold onto such a huge hold on the galaxy; meaning the losing player can actually fight back (this is called negative feedback in engineering).
Instead of when you conquer a planet and get 'paid' a bonus for it - make it cost you money to represent the choas of converting the indeginious people. Plus make the planet produce negative cash for you until it is developed with mining and buildings (this represents employment and wealth for the people).
I do not know though how to make a maintenance cost for space and ground units; but I can do the planets easy enough. This would help slow down a planet grabbing rush.
I think maintentance cost should have been included to counter balance the saddle point snowball effect of a galactic rush. If a wining team has 60% of the galaxy, you are pretty much going to lose unless you do this. Of course certain planets have strategic bonus and there are choke points etc.
So once the full real game is out (not the demo) if Rushing is a problem, there is some thing we can do to stop it (if it really is a problem). Else, people are just going to quit the game if your in MP once they start losing. Single player is no problem, the AI is never smart as a human.