So, I'm nearing the end of what is effectively my third re-read of House of Chains, by 
This book contains the best #worldbuilding I've seen in.. maybe ever?
Now, don't get me wrong - the prior four books in the series are also bursting with great worldbuilding and fantastic characters. Everything prior lays a foundation of understanding that is necessary for House of Chains to achieve the heights it does... but they pale in worldbuilding comparison.
I'm not going to really touch on the plot too much in this free-write thought vomit, but we'll brush up against some stuff so after this point:
THERE COULD BE SPOILERS.
Unrelated to worldbuilding, but important nonetheless, this book has - for me at least - the clearest theme of any of the prior books. House of Chains, at its core, is about Broken People. It's a theme that is so tightly coupled with HOW the worldbuilding is displayed that I think it's worth mentioning. It's masterfully woven through the narrative across all characters.
So, while I'm not going to touch on that much more (I don't think, this is stream of thought so we'll see where we go), it's something I want you to keep in mind.
We're in a world that is breaking... and has broken before. Time and time again. And in House of Chains, we're following people who have broken. Some, more than once.
We get hints of this in prior books, but none that drive it home as well as House of Chains does in my opinion - which is poignantly delivered in the opening scene, which takes place in a realm called the Nascent.
A world thrown into chaos, broken by a rift that has emptied an alien sea into it.
And there, atop a gigantic wall crumbling under the pressure of the foreign sea, a group of near-immortal beings is in the process of shorning one of their own... and chaining them to their fate of dying, broken and alone, atop a failing wall in a realm that itself is being broken, but, as we later uncover - is already broken.
For experienced worldbuilders, you might be already anticipating what I'm getting at by pointing out this scene - and maybe, you've already anticipated why I've thrown down the gauntlet in saying this series - and this book - has some of the best worldbuilding I've ever seen.
So many of the books we read only hint at history; they provide enough basic worldbuilding for the facilitation of the story they're telling, and in many cases that works and is fine.
Malazan doesn't go half way. The worldbuilding isn't tacked on to tell the story, it's built into the story. It IS the story.
The extensive history of the world underpins everything, and even when it's vague, it feels INTENTIONALLY vague. As an example, we know that one of the characters is descended from a fallen people, a shadow now of what they once were... and while their history is vague, I never get the feeling that it's a hand-wave because Erikson didn't know what the history WAS. I suspect that on some shelf, in some drawer, or tucked away in a file somewhere... there's a wealth of information about that fallen civilization that we never see.
The wars that the T'lan Imass fought, and the culture they have are generally background details (at least, they are at this point of the series) so we don't see a lot of it... but through Onrack the Broken, we get glimpse after glimpse at the depth of worldbuilding that underpins the narrative.
Further, this depth of worldbuilding allows Erikson to make references to ancient creatures like his K'Chain Che'Malle and while we (at this point in the story) don't have a LOT of information about their culture and their history... what information we do have is well crafted and well thought out. If what we have to this point in the series is all Erikson has written - he's done a masterful job of making it all seem a lot deeper than it is.
Given his background as an archaeologist and anthropologist however, I suspect that building histories was part of the fun for him and that there's more to everything than we, the reader, see. There's a complexity to the world that to me, as someone who builds ttrpg worlds for fun, speaks volumes about the amount of work that he and his co-author did creating this. The worldbuilding in Malazan adds a verisimilitude that takes the setting from being a backdrop and firmly thrusts it into being an integral part of the story, and makes the world real in a way that few other books I've read have ever done.
Now, part of this depth is likely due to the setting being originally their TTRPG setting. I suspect (with fairly high confidence) that there's historical events in the books that were actually games played at a table. Further, while I haven't checked into it (and this should be a note to self to do so later) I'm willing to bet that a number of the background characters were in fact Player Characters in their ttrpg games. Dancer and Kellanved (among others that are old members of the Empire) have a number of scenes where they just feel like someone actually sat down and was playing them. There's a point in House of Chains where a character remarks that an event well prior to the beginning of the series went off mostly well, and they only lost one member of the team - and the entire time I was reading it, it just felt like 'this was a PC character death, and it's made it into the novels'.
It's this kind of worldbuilding that, for me, really sets this series apart from so many other books. The world at every step feels lived in and well thought out. Magic doesn't feel like it was tacked on top as an afterthought - it's integrated into the world in a way that never leaves the reader feeling like it's out of place. Even things like the shape-shifting D'ivers (Individuals who can shift into swarms of rats, packs of wolves, etc - a many-to-one relationship) and Soletaken (who can shift into dragons, apes, and other singular creatures) feel like they are a natural part of the world.
Even magic itself - both divine and practiced - has not just a well-thought-out relationship with the world, but has an evolution in the world. Magic changes over eons, and that change is shown to us many times and in many ways. Old magics and new magics contend with alien, chaotic, and anti-magic elements... and it all is introduced to us and revealed in ways that makes it feel like it's just... part of their world.
There are, without a doubt, many great examples of worldbuilding out there to consume - but if you want my recommendation... and if you've made it this far I'm going to assume you do:
Pick up this series, and as you read it make note of the worldbuilding woven into the story. If you're looking for it... if you're mindful of it... I think you'll come to the same conclusion I have. I think you'll find that the quality and depth of worldbuilding in this series is an exceptional example of how truly great worldbuilding can make a world of difference in whatever you're creating, be it a ttrpg campaign, a novel, a comic, or animated media and movies.
Thanks for holding onto your butts and joining me on my nerd train. I've been thinking about these things a lot and I had to get them out.
I'll probably word-vomit about this series, and maybe even this book, again at some point. Maybe I'll try and sit down for a more structured blog about it... but not today. Today you get the nerd train.