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Sign ups closed

Thanks to everyone who has signed up!

There is just one participant who has come out of the initial stages of the matching process without any potential recipients. I have sent the individual concerned an email to the address they have registered with AO3 with some suggestions of how we can proceed; please respond within 24 hours, or I will (very sadly) be forced to delete your sign up in order to allow things to proceed.

Once I hear back from this individual, or after 24 hours have elapsed with no contact, I'll go ahead and generate assignments, initial pinch hits, etc. so watch out for something in the next 24-48 hours.
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One hour left to sign up!

If you are still in the process of signing up, please reply to this post or ping me an email at worldbuildingmod@gmx.com with your AO3 username so I can keep an eye out for your sign up appearing. I can't hold the door open indefinitely but I will do my best to provide a little bit of wiggle room.

If you are still signing up, and you're aiming to provide detailed prompts*, then for what it's worth I would quite strongly suggest that to be sure of making it in time, you go down the route of linking to a placeholder letter and cut and pasting brief details of your strong DNWs into the Optional Details boxes, and then update the letter later.

*please note that prompts are not compulsory - Optional Details Are Optional applies in all directions, and in this exchange in particular many of the worldbuilding tags are essentially prompts by themselves
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24 hours left to sign up ...

Here's the sign up form.

And if you're still on the fence, here's the tag set to tempt you ...
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Sign ups are open!

Sign up here!

I will shortly put up a post for "Dear Worldbuilder" letters and update the sticky schedule post with useful links for the sign up period.
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The tag set!

The tag set is now in its final form, for better or worse; if there are any remaining mistakes, I am afraid we will be stuck with them. Thanks to everyone who contributed corrections, especially the eagle-eyed Morbane.

Three Marvel characters decided to take a wander through the tag set, as is customary: Maria Hill, Tony Stark, and Scott Summers. To keep them in the right places, you will find that they have gained some repetitive extra bits to their tags; these can be ignored from the point of view of using them for your requests/offers.

I have turned the tag set into a Google docs spreadsheet here. This may be more useful but may also contain mistakes; in the event of discrepancies, the tag set on AO3 should be taken as definitive because that's what sign ups and matching will be working on. If anyone has suggestions for improving the presentation/useability of the spreadsheet, I am open to them (or if anyone wants to make a nicer version, I will happily link to that instead).

For those who are interested, the final count is 233 fandoms, 1677 characters (so 1211 characters outside "No" and "Original") and a whopping 1463 worldbuilding tags.

Sign ups will open very shortly.

ETA: Don't forget to check the Uncategorized Fandom section. All of Harry Potter and Middle Earth are in there, along with quite a bit of Star Wars. And many other fine fandoms.
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The "No Characters" Guide

The updated version of the rules says:

The “No Characters” tag in a prompt means that the requester is leaving the use of characters up to their creator. It does not prohibit a creator from using characters.

Including "No Characters" in the tag set for each fandom is designed to improve the chances of people matching to other people who want to receive/create the type of works they themselves are interested in, since some types of worldbuilding fanworks do not include characters in the traditional sense, or at least do not focus on them.

Here's how this will work in practice:

No Characters and Requests )
No Characters and Offers )