[Barnacle Bill]

On the subject of colonization:

I interpret "ice" as being frozen atmosphere, temperatures near absolute zero, etc... Life forms which evolved there would not be able to live in any other environment. There is a book which I think is titled "Camelot 40K" about such life forms.

Similarly, gas giant critters wouldn't be living on any other type.

The notion of anything like us living on either of the above is also an impossibility.

So, I propose the following changes:

You should need domes to live on the same planet type but with different atmosphere from your home world (as you do now). The "conditions" would refer to what it is for folks who can live there without a dome. For anybody who needs a dome, it would act like the conditions were at whatever the lowest rating is (don't remember off the top of my head).

If you convert the atmosphere, the conditions would gradualy get worse, until they reached the lowest rating just before the atmosphere actually changes. It then starts at the lowest rating for the new atmosphere and have to be improved via the appropriate facility.

There should be a special tech required to be able to build domes at all. It would take a special, and specially expensive, colonization module to implace a domed colony. That would only implace the population held by the colonization module itself (so don't bother with cargo storage on a domed colony ship). The population in a domed colony would not grow. You would have to build additional dome space in the planet's production que and transfer in additional people as cargo after the dome space is ready. The maximum population limits would remain as today.

It would take special techs to be able to colonize planets of another type from your race's environment (rock, gas giant or ice). Those techs would require developing the dome tech first, and allow building the special and expensive colonization modules for those planet types.

You would not be able to obtain the special techs for colonizing planets of another type except from another race of your own type. How a gas giant race colonizes gas giants is of no use to a rock race. How an ice race colonizes gas giants is of no use to a rock race, either.

You would either not be able to convert planets between types at all, or it would be very expensive (probably cheaper to build a ring world, if you think about it).

Building a planet from asteriods should be a project akin to ring world construction (only cheaper), not something done by a component. Blowing one up is fine like it is, though (lots easier to blow things up than to build them).

Finally, the number of facilities you could operate on a planet would be determined by population. It should take a nearly full planet to operate that size of planet's full allotment of facilities. The facilities in excess of what could be operated by the current population would be "idle". Idle facilities ones would be labelled as such on the facilities report, and you would be able to reorder the facilities in some list for each individual colony to enable the ones you want.