Once again:
EE: Mmmm, water and thin atmosphere.....
I did not study physics but I am pretty sure water world + thin atmo makes no sense.
(...)
Same as my initial thoughts, but then I remembered the (turbo) greenhouse atmo of Hyceans, so it kinda makes sense? See the Wikipedia article: https://en.wikipedia.org/wiki/Hycean_planet
I actually majored in Physics but I also wouldn't know

, except maybe for the hypothesis that evaporation seems a lot easier. I guess it would depend on the planet's mass and its gravitational pull.
The Hyceans that are generated by this mod seem otherwise in-line with the Hydrogen rich atmosphere description, they mostly have "Plentiful Volatiltes" as a trait.
But regarding your greenhouse remark, why would Frozen worlds make sense for hidrogen rich atmospheres? I'm not really seeing the connection you're seeing.
The Aztlan generated one just has the traits of a regular frozen planet, it follows from the procgen algorithm described by James in his post.
By the way: check the screenshot, there's another planet generated on the Aztlan system that is identified as an Ice giant but seems to have the traits of a Gas Giant instead (no cold).
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