I think that thay should make some planets biger than others and some smaller.
Also on big planet, they have more gravity so population groth should be slower but the planet has more room for more people, but on smaller planets they have less gravity so population groth should be faster but the planet is smaller so less people.
And, u could make research, that has something like antygravity, and orbitill structurs for smaller planets.
I lack the brane power to do so, so thats the reson i posted this.
ps: if it is not too much, and if u make this, plese put: idea by:Bla303
thancks 