The Broken Cog
By Doctor Necrotic
You clearly put a lot of work into this, and I also would like to see an expanded version.
My first recommendation would be to shift the timeline you put at the beginning to the end of the article; that way, people will have a better idea of what was happening when and to whom.
I liked that the various domains have such strong links, but I agree with Ian that introductory summaries of the separate domains and the Cluster at large would be good. The captioned blocks of information found at the start of the Gazetteer articles are in no way mandatory, but they're useful shorthand for readers to build their perception of your domains on.
*
Alleigosto. A land of progress, with a technophobic Darklord who wishes to turn back the clock. It works, and the Duke's acts of terror across the borders fit him well. If anything, he could be
more involved in harassing neighbouring domains.
* I really liked the concept of
Belagora's Darklord Hive. It's a fresh new possibility, and the notion of it draining the bodies of its constituents, then reanimating them as people puppets is chilling.
*
Darkheath ... had too much redacted and unexplained (albeit with helpful references to existing articles) for me to really get into it. :-/ The way it's currently written, it might as well be contested land between the other more bellicose domains without a lord of its own. I did like your description of the various departments and their grim commitment to a sunk cost fallacy instead of trying to actually end the war.
*
Ichthyos: I see you there, 'Obed' Elos. Obed Marsh, anyone?

This whole domain seems like Innsmouth writ large, with the domain's curse of being relevant only as a producer of food instead of a nexus of culture and learning very appropriate to a Darklord who sold his soul for material wealth and physical immortality. The 'distinct color' reminded of Lovecraft story
the color out of space; will we learn more of this in the expanded article?

*
Nosos, Nosos, Nosos... One of my least favourite domains - but this is in no way due to your skill at writing about it! The idea of having to pay a subcription fee for fresh air and water is not a new one, but it is still chilling in its implications. I like that Malus is not simply chided and made to feel guilty by nature, but that he is cursed to share its suffering. Another reference to the
color out of space makes me wonder whether this taint is shared between Nosos and Ichthyos in spite of the intervening sea. I liked Dr. Herman K. Wilder at least speaking up for the Noson people's suffering under their dehumanizing conditions of filth and pollution. The nod to SCP - D-class - was amusing in itself, but makes me wonder whether you'll do more with this.
* The concept of
Rockbaecche reminded me initially of
Twelve Monkeys - the main difference being that the lunatic who unleashes the plague is driven by a desire for power and control, rather than someone desiring to preserve the planet at the cost of humanity. Regrettably, motivation is not as important as result. The description of Rockbaecche's society brings back unpleasant memories of the height of the pandemic.
*
Zherisia. I assume you redacted several points of information because they've been handled in other resources, but I think it's a shame; these redactions break the flow of an otherwise enjoyable article. Giving back the Zherisian countryside, and causing culture shock by having everyone there appearing to have been in stasis, was a clever idea; the Zherisians are still trapped by
appearance, but now they're desperately clinging to a semblance of normalcy rather than concern about impostors in their midst. Malachi Cross's tale and his epithet of "the Barmy Bomber" reminded me of the Paridoner tabloid rags; well done!
One thing I missed in this article is a writeup of the major players. It would be nice to see their powers outlined a bit more than just the class + level description, if or when you get around to the expanded article.