[verzali]

Those rogue worlds are frozen though, the only source they have is from radioactive decay in their cores. And eternally dark, since they have no Sun to light them.

It would make more sense to use fusion reactors to power colonies in the outer reaches of the solar system than to go to a rogue planet.

[kfuse]

Jupiter is 5 times farther from the Sun than us, there is basically no lighting and heat from the Sun there.

I think for a civilization capable of sending reasonable amount of people people at reasonable speeds to colonize such planets, creating suitable atmosphere, lighting and heating is very much possible. Gravity is the only hard requirement.