There could still be a basic underlying plot for the gamers to build from.
For example the hub might be a dimensional nexus under attack by beings from the various worlds it links and each quest might serve to stabilize part of the station.
Or the goal might be "Tell the story of the great war between the lands of Lilidis and Empyrea." The framework would then be a timeline of war, with the game being essentially a round-robin story.

You could do the hub think like in Phantasy Star online where you can go and get supplies or whatever there and then go to the playable areas in a teleportation portal with each area being unlocked as you go.

That's the best way I can think of having an at least somewhat cohesive plot and the hubworld thing.

THat's kind of what I Was thinking, though I've never played that series. Also each successive person should keep in mind what's gone before and build on it- not that I think most people here are the type to merely throw in stuff with no regard for continuity, mind you, but such things have been known to happen. So when the game gets to your turn, HB, see if all those epic ideas still make sense before proceeding.
Like I said, another idea is to actually agree on a general outline before beginning the game, which people would try to stick to to some degree.

While I'm still thinking it over, I'm considering taking a section fairly late in the game. Since I'm fairly new to actual game making it would be easier to start by building on the systems and elements already set in place by others; it would also give me a chance to close any gaping plot holes.

say, what's the setting? so that I can make use of my container houses

THat's kind of what I Was thinking, though I've never played that series. Also each successive person should keep in mind what's gone before and build on it- not that I think most people here are the type to merely throw in stuff with no regard for continuity, mind you, but such things have been known to happen. So when the game gets to your turn, HB, see if all those epic ideas still make sense before proceeding.
Like I said, another idea is to actually agree on a general outline before beginning the game, which people would try to stick to to some degree.

The idea of a hubworld is a good idea if it's implemented where we can visit each section in a non-linear, or at least semi non-linear fashion, with some sort of loose but not neccessarily direct connection to each other. The creator shouldn't feel constrained by having to build upon the previous part to retain continuity, since the purpose of the chain game is to add our own distinct sections. Besides that, it adds variety in each playthrough by giving the player the choice as to which section they want to play through and complete first. 

The only aspect that I agree should be 100% consistent is the visual style, in order to have variety but retain a certain evel of cohesiveness.

How's this for a storyline that implements the hubworld where each section is completed non-linearly. I just came up with this so it is somewhat vague but the central idea is still there! The main protagonist could become marooned on an alien planet that is colonized by humans; I chose humans as to not make it feel like a sci-fi game, although the theme depends on the respective creator's whim. There could be the hubworld and then a means by which to visit each section, whether it be by a boat, descending an elevator to some secret laboratory, or entering a portal created by wizardry. Either way it pans out, in each world is a piece of a spaceship or another mode of transportation that must be collected in order to assemble the entire vehicle in order to return home. You can enter an area in the hubworld and assemble the vehicle piece by piece, and you can collect them in any order that you desire, but each piece is just as important as the other.

And then at the end of the game we can create an epic scene where the protagonist is departing back home through the cosmos as we display the name of our fellow GamingW members.

In fact, it doesn't have to neccesarily be a planet that the protagonist is marooned on - it could be an island or something else that requires you to assemble a vehicle to finally leave. I dunno, any thoughts or comments on this? I think it could work, but we need a consensus here.

not gonna take part BUT i definitely would love to see you guys finishing this! i will play for sure.

I see no reason why it has to be completely non-linear. People can be plenty creative within the constraints of the past or throw in a shocking swerve if they must- it's done all the time in round-robin stories. . . there are connections, if loose ones, in each part.  For example, in  Little Women, the group takes turns telling parts of a story, part of which runs like this...

 a terrifying evil spirit, blocking the heroic knight from entering a room,  threateningly holds out a mysterious object. . . which turns out to be a snuffbox. When the hero takes a sniff and sneezes his head off, the demon packs him in a box with a bunch of other headless knights who. . .  begin to dance a hornpipe as the castle transforms into a ship. The ship fights some Portuguese. . . but eventually sinks to the bottom of the sea, where the box of headless knights is found by a mermaid. . . 

you get the idea. However, all I'm really requesting is that people do their best to tie up any loose ends by the time the credits roll.

I was actually inspired with an idea today and was gong to ask if i could go first, to set the tone, but I see Thecatamites has already begun. Well, Cat? Would you mind swapping?

The basic idea is much like the "nexus of dimensionless" Cat was talking about.

I'd like to request to be 4th or 5th in the chain. That way I have an idea of what people have done, but don't have to play thru the whole game to do so. :P

Hmm, a good reason to be in the middle, if I can't start, or near the end, to tie things up. Part of me suspects that thecatamites (AKA Cat) is somehow going to work in Disney's Doug, as he said the idea should be "funnie." I've been experimenting and attempting to whip up a title screen for the project- yes I know Cat will probably do one but i had some ideas of my own as well.

I see no reason why it has to be completely non-linear. People can be plenty creative within the constraints of the past or throw in a shocking swerve if they must- it's done all the time in round-robin stories. . . there are connections, if loose ones, in each part.  For example, in  Little Women, the group takes turns telling parts of a story, part of which runs like this...
 

You're right, it doesn't have to be non-linear to be successful, and I have an affinity towards non-linear/open-ended games which makes me more in favor of them, anyhow. Still, I like the idea even if it isn't neccessary; I feel that creating distinct parts for each person would be more successful than trying to create a coherent series of events. In the former case, I can't help but to feel that the game will begin to not make sense at one point if we aren't careful and meticulous with how we coordinate with each other.

Anyhow, I've never even done a chain game before, so maybe I am just talking out of no where - maybe part of the fun is just finding that certain way to add onto what others have done before you. Either way, It would be nice to have a more fleshed out plan of how we're going to put all of this together to keep any confusion or misunderstanding at bay.

Like I said, another idea is to actually agree on a general outline before beginning the game, which people would try to stick to to some degree.

I agree and this is what I am alluding to here. I wonder what kind of progress TheCatamites has made so far?