Giant Stars?

[Mylon]

Is what I don't understand is if you can build ringworlds/sphereworlds out of nothing, why can't you build planets in the same manner? I understand the game balance aspect, but it does seem a little silly, anyway. Sure, the ringworld/sphereworlds need a star, but that's for energy, not for actual building material. A planet that doesn't have a star would have to produce its own energy, and a huge amount of it, and would have a limited lifespan unless people brought in water for fusion or some such.

Now, is what really bugs me about ringworlds/sphereworlds is they they really should take up more than one square. Like a radius of 2-3 for both. At that point, it might be better to call each sector a "planet", which would alleviate the problem of taking forever to fill a ring/sphereworld. In the ringworld series, the ringworld builders collected all of the mass of the system to built it, so those 5 huge worlds worth of ringworld were at the cost of everything else in the system.