I have an idea of a catastrophy, a karstic planet that has oceans that return every 300 years or so. I got the idea from guardians of the galaxy, the first planet we see.

Or an ocean world turning into a kartic world... ice age events, diiscovery of inteligent life on a cave world, etc.

add specific desticts based on the enviroment of a planet

subclass specific building chains =, like hydro or fish harbours for wet types, or ocean planets. mass converters for plant heavy planets like tropical. and since theres world classifications like refinery world, argi world and so forth, you can also tailor buildings for those. just a thought.

evacuation decision to instantly turn a planet to emigration or make resettling cheaper (is there a planetary modifier for resettling or only empire wide?) maybe emergency shelter buildings to protect a planet from total wipeout? also, as i just recently found out, ecumenopolises shouldnt be totally desertified. it would be better to just insert some blockers and destroy some districts so you could at least reclaim some of it. i think blockers are a very good thing anyway for most of the bad stuff.

new events: many of the spaceborne aliens have not much stuff to do, so why not let them visit. some mining drones trying to strip mine your new colony or some tiyanki trying to breed with your civilian spacecraft or spontaneous void cloud formation in your black hole systems.

How about a nanite world about a civ that created them and had there world destroyed

There is an event where you find ancient terraforming equipment on a new settlement, and if you reactivate the equipment one of the outcomes (or the only outcome) fills the atomsphere with ammonia and it becomes a toxic world, but the planet still has an ammonia biosphere (ammonia plants and animals). Maybe you could do something for that?

Originally posted by R.Windu:

There is an event where you find ancient terraforming equipment on a new settlement, and if you reactivate the equipment one of the outcomes (or the only outcome) fills the atomsphere with ammonia and it becomes a toxic world, but the planet still has an ammonia biosphere (ammonia plants and animals). Maybe you could do something for that?

I had plans for the ammonia worlds, on the site it even remained in the description of stage 2. But I think this should be further discussed. In the future, I will choose a site, for example, a reddit, and we will talk about it in order to decide whether to add such worlds or not.

I just had the Ancient Caretakers ringworld home star go evolved_star and destroy them before they even had the chance to wake up.

As thankful as I am for getting all of their systems, I'm not sure this is a good idea to keep as a feature. Especially for smaller maps... :P

Make tomb world variants. As a disaster have ancient robots or survivors of the old civilization rise up and attack the colonists or a colonist accidently activate the remaining nukes on the planet.

mabye a diamond super planet made out of diamonds, gives off alot of minerals but is extremely rare, yes they exist https://www.space.com/23138-diamond-planet-super-earth-discovery.html
https://en.wikipedia.org/wiki/55_Cancri_e

- A double planet a Roche World like Rocheworld (R.L. Forward book)
- A world with a kind of ocean lliving like in Solaris Movie.
- A planet with floating islands like in Pandora (Avatar)
- A planet with several rivers and a big equatorial one as Coyote planet ( Allen Steele book)
- A Tidally locket planet
- A non spherical planet, with a very big impact crater, from a recent catastrophe
- Volcano world
- A diamond world ( pure carbon planet could be sci. possible )

A world that is completely flat - Just endless stretches of plains. it would have no exploitable resources like minerals or energy but it would be easy to build on since there are no planet blockers.

A hotspring world with flowing geysers and hydrothermal features. It could provide planet specific buildings which generates energy resources.

A world where a singular parasitic organism has stretched all across the world, suffocating the natural landscape and toxifying the fauna and flora. Think sorta like the blood weed from War of the Worlds. Events could include trying to destroy the pathogen from the planet or using it to become a bioweapon which could give bonuses to bombardment damage.

Tomb world variants would be awesome. Like a dead world - endless stretching megaopolises' and manufactories litter the planet which could provide bonuses to minerals and alloys. Acid rain worlds where noxious gasses and pollutants fill the clouds as it rains onto the the ground where it destroys buildings and pollutes wildlife.

Idyllic worlds which are not as perfect as gaia worlds or provide the massive habitability boost but instead provide immigration pull and extra growth along with a hapiness boost from the stunning natural beauty.

The are countless possibilitys, because the will be many outcomes for different Subclasses.
How about that some time after the Colonisation, the sub Class would be come up as an Event. Because the Colonist trigger something, what the scientist didn't detect at first.

I think a Plains world sub class would be cool.