I would love to see some more world types in the game, especially for the tier that requires atmo cleansing tech, giving more reasons to colonise late game. This is the reason precursor worlds is my favorite dlc. The precursor planets makes the galactic geography much more interesting, and the variety in visuals is always good. It's one of the reasons I like Endless Space 2. They have a way of making planets look and feel unique.
My initial ideas:
Phase world: A paradise world that exists in the space between multiple realities, which provides boni to food production. Contains a mysterious wonder improvement that enhances various forms of production.
Tomb World: A planet littered by the monolithic remains of a seemingly long-dead species that ruled it aeons past. Megalithic structures that stand as monuments to the past hide within them unique pieces of technology waiting to be discovered.
Dread World: A world which was once a vanguard for the extra-dimensional dread lords lies abandoned, with strange organic infrastructure that provides production boosts to those who can reactivate and exploit such technologies. However, colonizing may come at a price...
Dream World: "Is it real? Were we ever there? As I disembarked the UCS Deliverance for what felt like.... What is that sense...? A simultaneous keening and comforting sense of deja vu.... Again? My booted feet landing on the lush grasses of this strange planet we unceremoniously logged as Canaan 426. On another world.... In another life, I may have been taken aback by the sight of all my loved ones. Those I had lost or had become estranged to in the ravages of this life. Walking to me, arms open, eyes beaming. Smiles more familiar than familiar, bringing evocations of the most comforting, intimate embrace. All this. surrounded by a blurry, picturesqueness of a dreaming, underneath a canopy sky of cascading color and vibrancy.
I had just arrived here, and yet I had never left. This world of dreaming."
- Provides high bonuses to moral, production boni to citizens. Gives free citizen upon colonization.
Oh yeah, just putting it out there. You take many of the ideas from this thread and do a special planets dlc, I'll be happy to put money to it.