give feedback on how to develop my fantasy world

[snooker]

So I took some base ideas and fleshed it into a world (mostly barebones for now, I just needed a backdrop for my custom system im making). I'm looking for feedback on how to make my world better and more unique.

My current idea is that there are three playable races (as in sentient humanoid races) each inhabiting their own planet -- the cambion (I don't have a better name, and they aren't related to demons. represents the poles and the golden horde), the elves (my in-world nordic analogues, and also with a bit of fae lore in it), and the humans (I've got several main cultures for them; angles, gaels, saxons, franks, and berbers).

My older idea was that there would be four main races (the fourth being giants), and each being descended from a group of immortals. The cambions' precursors are the fiend (no link to my current demons), the elves precursors are the fae (also they are a lot more regular fantasy elf than my current incarnation), and the humans and giants are built and used as a weaponized race, whereas the original immortals and race of their planet have long since been wiped out.

As for the cosmology, the three planets (plus a fourth one which I currently am unsure about, or even if it should make the cut) make up the basis of "realspace", and the other creatures are "demons" or "spirits" from far beyond, who project their spirits into realspace.

Of course, given that they are only spirits, the only way demons can manipulate this world is by possessing people or animals. Slowly, over time, as the demons personality subsumes the hosts, the shape of the hosts body also warps to represent the demons true form (le eldritch horror time).

These demons work on behalf of their leaders, le funny eldritch horrors, who seek to convert as many people to their cause so they can finally enter the world and reshape it in their image. How? Soul power.

Souls are extremely powerful, and before they died, the living gods harvested people for their belief and souls so they could remain powerful. They were struck down by a mortal taking a page from their book and running off of the souls of everyone who he has ever killed, directly or indirectly, through his wars.

The demonic leaders try to coopt the power of souls the way the old gods did -- getting mortals to pledge themselves to their cause, and then building a portal out of said souls. Luckily enough for everyone, the sheer number of demon lords fighting against each other for souls ensures that, for the last few millennia, no one has come close to summoning their leader.

The old canon was that demons were results of experimentation on elves, humans, and other creatures by the cambion and fiends. Not as flashy, but I suppose its unique.

How is it so far? Anything I should change, add, or modify?

[Pandamonium]

It sounds fine so far, possibly tie in the 4th planet to the demon lore?

Other than that it is kinda hard to answer without knowing what you are aiming for, do you have specific thoughts you want to flesh out?

[snooker]

It sounds fine so far, possibly tie in the 4th planet to the demon lore?

Other than that it is kinda hard to answer without knowing what you are aiming for, do you have specific thoughts you want to flesh out?

Right now I want opinions on my existing cosmology; and once I've got that down, I'll focus in more on the conflicts and kingdoms of the planets (may be hard because I need a map and I'm not particularly good at mapmaking)

[Onos]

So, how "real" are you aiming for the solar system to be? There's a lot of variance with things like climate and orbital period you could go for. How easy is it to travel between worlds, with and without magic? Do the moons have any significance?

What's the mechanism behind demonic possession? Can it happen to PCs? How quickly can the corruption take over? Is it possible to travel to the spirit/demon realm, physically or otherwise? If so, what's it like?

How close to D&D are you aiming with your original system? How do the gods work and where do they reside (if any survive)? Are there any other important planes (elemental and such)?

You could certainly still go down the "experimentation" route regarding demonic origins - maybe the missing planet was shunted off into some sort of magical plane?

[sktarq]

Well what I think of your cosmos really has to do with what kind of games you want to run in this realspace.

What kind of tech level, high or low magic, do you plan to have planet hopping being a thing that is common? does each planet have large populations of the other races? What kind of feel are you aiming at? Do you plan of pushing the dungeon delving, social challenge, etc. What are you aiming at for characters to do as they climb levels (more weird monsters? increasingly multiplanar? other high level humanoids? different areas from most low level areas? etc are all normal but the balance between them varies a lot by setting) Themes you want to emphasize in worldbuilding? (fate, bloodline, magic-needs-sacrifice, cyclical power, man-vs-wild, et etc)

because if you understand the feel of the game you want you can bake it in all the way back into the very nature of the cosmos.

but so far it looks like a fairly generalist if blocky structure....you have a teifling/orc type planet, an elf planet, and a human planet (with possible giants either having their own planet or scattered on the others)

I will also say if there are multiple human cultures I'd have to ask why the elves and cambions don't have a variety of cultures at least on the planets they dominate.

[brian 333]

If you want your world to have depth, give it stories, myths, ancient poets and playwrights.

This will also fill in gaps in your lore and answer questions you never thought to ask.

(Transliterated From The Elvish:)

Beware the beast most foul and blighted,
Who came to us in our time of need,
In noble guise and fair of form,
To defeat our foe we were united.

From forests hacked by bloody knives,
Our kinsmen fled in desparation,
To hills and mountains far and wide,
In secret forts they hid their lives.

The Cambion King stalked glen and field,
Seeking secret paths and stations,
To slay any who would defend their kin,
Enslaving all who chose to yield.

And yet did always our kinsmen clever,
Find ways to sneak and to evade,
And build defenses in trackless places,
The foe could seek but find them never.

Then AiElgairien Eagle Eye the Eldest,
Seeking refuge for a new fortress,
Came upon something new in the world,
Whether friend or foe he could but test.

Watching from afar he followed,
And day by day saw what they did,
When cambions attacked his newfound friends,
Their deaths could not be allowed.

They joined and fought the day and night,
'Till the last Hell-spawned was slain,
AiElgairien spoke of their common foe,
They swore then they would together fight.

For an age the humans served our kind,
And bred to fill our fortresses,
Driving cambions away with their numbers,
On this point yet our kin were blind.

When the great war ended it was man,
Who surged across our vacant lands,
Taking our abandoned fields and cities,
Leaving we who saved them to live as we can.

The nature of men can be good or ill,
Their promises can last or they can be fleeting,
It matters not because their brood,
Will grow until there is no place left to fill.

Artist unknown, lyrics transliterated by Nairb, 3224 Juliean Calendar.

[Geordnet]

My question for you is how do the inhabitants of your setting know that the other three worlds are the "wandering stars" in each others' night sky? (Unless they don't know.)

Did some genius proto-scientist hypothesize heliocentrism and use coordinated observations from multiple planets to geometrically prove it? Or were they simply told so by the gods?

Also, I'm wondering how you've got so many planets in the habitable zone... It doesn't seem gravitationally stable.

Unless the star is a red dwarf, which would make years short, or they're all moons of a single gas giant, which would mean frequent eclipses. (In either case, there'd probably be some orbital resonance...)

I suppose you could also make one pair of planets a binary, to reduce their orbital "footprint". (That probably wouldn't work around the gas giant, though...)


EDIT:

I've figured out another arrangement:

Start with a class A or F star (bigger than Sol but not Giant). Put a super-jupiter or even brown dwarf in the habitable zone. (The high masses of these two are important for orbital stability.)

Put one planet each in the leading and lagging Lagrange Points. They'll have the same year length (longer than Earth's) but the seasons will be out of sync. They're also more vulnerable to solar radiation (in a "you get skin cancer" way, not a "oh its so hot" way).

Put two orbiting the gas giant with different periods (possibly with a resonance like 1:2 or 2:3). This could be anything from a few (Earth) days to a couple months. These planets' seasons should be synchronized with each other, and (for distant orbits, where the gas giant doesn't fill such a huge portion of the sky) eclipses should only happen in spring/autumn.