[Fyron]

I am wary of using combinations of gases without redoing the existing atmosphere types to match (eg: Oxygen/Nitrogen instead of just Oxygen). I'm not sure if people would generally prefer combinations or just single gases.

StarShadow said:
Also, generally speaking, as far as the atmosphere types go, wouldn't they just specify what the 'majority' gas is?

SE4/5 specify atmosphere as the gas respirated by the sentient race of the planet. SE3 was a bit different, with atmospheres like Oxygen/Nitrogen, Argon, Carbon Dioxide/Nitrogen, Hydrogen/Helium, Chlorine and None.

Will said:
I don't quite see why noble gasses are necessarily ruled out. It doesn't quite fit into the current game mechanics, but it is conceivable to have lifeforms that depend on a non-reactive but pressurized atmosphere.

If we can't think of anything (consistent) to fill the 10th slot, I would be willing to go with Argon for historical reasons.

AstralWanderer said:
Unless there is intended to be some gameplay variation (e.g. cost/capacity of domed colonies varying by planet atmosphere), what purpose would be served in adding further types?

What purpose was served by adding red giant systems? Neutron stars? 20 different kinds of nebulae systems stemming from 11 storm colors? Swirling WP graphics? Electrostorms?