Question regarding the Shardworlds

[scudalarm]

I have question regarding the Shardworlds:

1. Yolen is the most Earth-like from what I've read, Is there any particular period on Earth's history? Is it pre-industrial revolution? or Mordern-time in which we have the global warming issue?
2. Is is safe to assume Sel is just like Yolen/Earth, a terrestrial planet with diverse Biome (Forest, Desert, Grasslands, Coastal Regions, etc)  just bigger?
3. Among the Published work I read, Roshar felt the most unique, has it always been like that even before Honor and Cultivation?
4. Was Ashyn and Braize more like Roshar in their earlier periods? 
5. Scadrial was a creation of Ruin & Preservation, does it mean the whole Scadrian Solar System was a creation or just the planet? or just the lifeforms?
6. Can we have more details regarding Threnody? so far I visualize the world as 2 huge continents, one is Woodlands with some patches of Homesteads and Small Towns and the other as an "Evil Forest" dungeon type, also that there are always killer shadows outside.
7. Taldain is a huge desert planet, just like that "other franchise"...
8. But Taldain is  2 for the price of 1 world, that it has a darkside world .
9. Drominad System, we only have a book on the First of the Sun, and the place feels like a "Tropical Paradise", (my examples are Hawaii, Phuket, Boracay, Maldives, Seychelles), but with a twist, the Tropical Paradise wants to kill you. So does all the habitable planets in the Drominad System like a Kiler Tropical Paradise? are there variation like Killer Grasslands? Killer Mangrove Forest?

[Scion of the Mists]

1. Part of Yolen is very Earth-like.  But there's also a competing ecosystem that is very much not Earth-like.  
2. Yeah, Yolen, Sel, Scadrial, and Nalthis are all very Earth-like (with the exception of the magical components).  
3. Roshar is the standout from the other major Shardworlds, in that it is completely infused with magic and everything was developed to survive in the presence of the highstorms.  It was this way even before the arrival Honor/Cultivation.  The spren (including the Nightwatcher and the Stormfather) and the highstorms all existed prior to the arrival of the Shards.  Everything is crustacean-based - Brandon drew inspiration from tidal pools.  Most of the normal Earth-like things (birds, humans, horses, etc.) came later.  
4. We don't have much to go on, but Ashyn was populated by humans, instead of Parshendi, so probably not.  
5. I don't believe they created the whole system, but I don't have a source for that.  Khris says in Arcanum that the planet was "likely" created by the Shards.  
6. We don't know much about Threnody - we'll just have to wait for the novel.  

Have you read Arcanum Unbounded or checked out it's Coppermind page?  Most of the info about the minor Shardworlds comes from those essays.  

Edited May 14, 2019 by Scion of the Mists

[Weltall]

To add some more information to what @Scion of the Mists said.

1. Yolen at the time of Dragonsteel is bronze-age. This can be seen in the excerpts Brandon shared to show the origins of Bridge Four and he's mentioned the fact in WoBs as well. The technology to make steel exists and is widespread among the Sho Del but humanity is still mostly restricted to bronze.

3&4. Adonalsium created the entire Rosharan System and most of the life found there is the result of evolutionary processes, albeit ones with an obvious magical component. Ashyn was originally much more hospitable to humans before the events that forced most of the population to flee to Roshar.

5. Only Scadrial itself was created by Preservation and Ruin but they created the whole world, not just the biosphere. It's why Scadrial has the same size, gravity and atmosphere as Yolen and why its ecosystem is a copy of the non-fain bits of the Yolish one. IE, it's why Scadrial is the Cosmere's Earth-analogue.

7&8. Dayside is largely covered in sand (albeit with a lot more water and some very large mountains) while Darkside is something  So yeah, half the planet feels a bit like Arrakis. We know this planet isn't stable on astronomical timescales but it's stable on the scale at which the series works.

9. We don't know if the other worlds in Drominad have manifestations of Investiture like First of the Sun does or if it's restricted to the one where Autonomy's Investiture is concentrated enough that a stable Perpendicularity has formed. Two of the worlds are inhabited though, so their ecology can't be completely lethal. What we do know about the other worlds is that they have different names for themselves than the chart gives for the planets.

Edited May 14, 2019 by Weltall

[Lightblood]

3. Roshar was already there pre- Shattering so they already had many of the things that make Roshar unique, including highstorms

4. Ashyn was certainly not like Roshar as it had stuff like soil and birds and horses. Roshar is all rocks with the only soil (in shinovar) coming from Ashyn with the humans during the fleeing of the "Tranquil Halls" aka Ashyn

6. Two continents the bigger one being taken over by "the evil" and the smaller one has the forest of hell, it is not made entirely out of the forests of hell. There are also other places and even outpost castles.

9. Not everything on the first of sun wants to kill you. Just Patji.

Edited May 15, 2019 by Lightblood