I particularly like the suggestion of running is as a variant setting for Metamorphosis Alpha... a generation ship which may or may not have been built by humans, but we're in there now, along with a bunch of other things.
Or maybe some hyper-weird take on Rogue Trader, set on some huge Tyranid hive ship that's developed amnesia/personality disorder due to damage caused by an Imperial Guard assault that left the attackers trapped inside.

Quote from: deadDMwalking;711497I hate to be a negative Nelly...

Well that's the whole point of posting publicly, isn't it? I need to hear about potential problems.

QuoteOn the one hand, while that might be the nature of the world, do the PCs have a way of determining that's the nature of the world?  

I'd say their world was devoured recently (a few hundred years ago) and the historical record is intact enough... or maybe there's some doubt about the record and perhaps the "lost" world never really existed? Why are there survivors from this devouring and not previous ones? Mystery, mystery...

QuoteDo they have a way of interacting with the creature in a meaningful way?

I suppose one plot line could be this: The most advanced of the civilizations inside the beast has claimed the area around its brain and has been trying for years to seize control of it.

Trying to destroy the creature would be a bad idea as that would leave everyone stranded in vacuum.

QuoteWhat type of stories do you think you'd be able to tell that aren't supported by a more 'standard' world?  

There have been some excellent suggestions in this thread so far. Here's one story - The heroes are trying to either seize control of the creature to "pilot" it to a new, real world for colonization, or gather the material necessary to build a fleet to escape from it.

QuoteIt seems like you'd be getting rid of a lot of things that people tend to expect.  Normal weather, celestial events, etc.

Well yes, it wouldn't be your typical fantasy and I'm aware of the warnings against excessive exoticism at the cost of accessibility. But sometimes bog standard fantasy really starts to feel like bog standard, and you crave something wilder.

Anyway, I'm considering just gradually building the setting right here in this thread if I can find the time between sessions of my 7th Sea campaign. Perhaps its fatal flaws, if it has any, will become clear in the process.

You know, the hoary old "(dark) magic is dying/corrupting the world" overarching plotline probably takes a different dimension if the world is in fact a giant monster...

Quote from: deadDMwalking;711497It seems like you'd be getting rid of a lot of things that people tend to expect.  Normal weather, celestial events, etc.

But you can substitute them with similar things... with a twist.

Gastric tides, intestinal earthquakes, platelet rains...

Energy sources: methane, electricity (by tapping on the nervous system activity)...

Materials: bone mining, all kinds of living tissues (maybe they have developed some technique to control tumor growth in some areas).

A question: is this setting leaning more towards fantasy or sci-fi? Do you (or your players) need some logical explanation regarding things like gravity, atmosphere, sunlight and their effects on human physiology?

Quote from: Frundsberg;711613A question: is this setting leaning more towards fantasy or sci-fi? Do you (or your players) need some logical explanation regarding things like gravity, atmosphere, sunlight and their effects on human physiology?

As I'm inclined to make this my personal "D&D with a difference!" setting it would likely be fantasy but with elements that resemble scifi, especially for certain factions and areas of the beast. Spelljammer comes to mind, but with more of an inner-space vibe.

How so many of the creatures from the devoured world are able to survive without supposedly essential things like the sun could be one of the setting's mysteries. Some would take it as proof that the devoured world never existed, others that the beast is benevolent and using magic to sustain them, and others still might argue that first generation of the devoured must have altered the physiology of their children to survive and further modification is possible and necessary (transhumanist cult?)

Alright, I'm at a thematic crossroad on this right now.

Should I have this living world obviously laid out like an animal (head, body, propulsion limbs, linear and mostly symetrical organ layout) or should it be more like a "flesh sphere" with an internal geography of redundant organs (multiple hearts, stomachs, nerve-cluster brains, etc.) that is difficult to make sense of for the humanoids living inside it?

The advantage of the first one is that world's creature nature is much more apparent and orderly. Its place in the universe is clear. This allows the heroes and their societies to plan obvious and interesting long term goals without as much philosophical uncertainty.

The advantage of the second is that it's much more mysterious. "How can be sure there is an 'outside' to this beast? Perhaps it just stretches on forever in all directions. If there is no outside then perhaps our original world really is just a myth... so where does all the food we see flowing through its system come from? What is the nature of the universe?" etc. It can also use a much more conventional setting map, albeit an 'underground' one.

Which would you prefer to play in?

I prefer the second.  The less you commit to up front, the better.  Also if you illustrate a head, you run the risk of people concocting 'stab it in the brain' type ideas.

Shit, Magic: The Gathering is going to do this idea eventually, isn't it? I mean look at the speed they're burning through every conventional and weird fantasy setting they can think of. They've already done what I consider to be one of the definitive visions of a technological fantasy setting that is NOT scifi (Mirrodin), how long before they do "an all living world"?

Quote from: Shipyard Locked;711863Shit, Magic: The Gathering is going to do this idea eventually, isn't it? I mean look at the speed they're burning through every conventional and weird fantasy setting they can think of. They've already done what I consider to be one of the definitive visions of a technological fantasy setting that is NOT scifi (Mirrodin), how long before they do "an all living world"?

Technically they already did, Rath was a world fashioned out of living stone .

Both approaches are viable. Remember that also the creature can have similar, but ultimately alien structures (heck, cows have how many stomachs?). There is also a certain temptation, or would be on my part at least, to just take a snake/cockroach/goat and enlarge an anatomical drawing of it, then say it is game's world .