...I'd advise against establishing a very large and well-detailed locale, as part of the fun is creating that locale in a shared effort, along the way, and too many restrictions on the settings might put off potential participants....
Naturally, a serial mod project could be tailored to any preferences a majority of potential participants might desire. I was speaking to ProphetSword's central suggestion of a "same location" theme as opposed to the very loose restrictions of the previous serial.
It seems to me that the less firmly established and detailed the location (leaving more for individual authors to construct themselves), the more it would share the same, or similar, potential pitfalls of the previous project.
While the authors would not now be writing cliffhanger chapters, they would be building on each prior installments additions to the location. Where the previous project produced an increasingly more convoluted plot, the new serial might produce an increasingly complex locale, thereby increasing the probability of continuity conundrums. The more the complicated the location, the less storyline flexibility for following authors.
For example, take as a locale that of a desert island, maybe like Gilligan's Island
. Very simple. The castaway's huts are at a given location, there is a lagoon, a volcano, hot springs, caves, and such, plus the wreckage of "The Minnow" boat. It has a wide variety story possibilities, enough to fill several seasons of TV episodes and more, with only the original set of restrictions maintained. But what if one story, in the middle of a season, established that there was a large cannibal tribe that also lived on the island and called it home (not just temporary visitors)? Future stories would have to take into account the presence of those native cannibals (eliminating or altering many story possibilities), additionally, in some already-aired stories retro-continuity errors would then be created (for having treated the island as previously uninhabited). Imagine more such additions to the locale, overpopulating the desert island with other indigenous tribes. Or another writer, later in season, decides that there are other, older shipwrecked boats in the lagoon, and other groups of pre-existing castaways. Can you see how unbridled additions to a locale can be just as perplexing to continuity as runaway storylines?
Many older television shows are excellent examples of how a firmly set central location (with a status quo returned to at the end of every episode), can host all sorts of interesting and exciting stories for continuing characters: Gunsmoke
's Dodge City, Dark Shadows
' Collinwood, Hogan's Heroes
' Stalag 13, even Star Trek
's mobile Starship Enterprise...