I think I may have discussed it before, but there are things that differ, fundamentally, from playing D&D and writing, and I think the reason I have such a hard time when writing novel-length endeavors is because I'm stuck in some kind of D&D mode. I finally finished my second manuscript (a clockpunk piece set in 1486 that follows the PoV of a Florentine spy and a Roman nun) and only now have I begun to break out of my DMing chains in writing long-form work. For some reason short stories and I don't have that problem -- maybe because I've written so many of them over the years that my style has been allowed to diverge from the way I run a D&D game.
The precise problem is easy to trace: an overabundance of descriptive words which hangs up the action. In D&D, every time you see something new you have to have it described in detail. Those details matter! They allow your players to make complex decisions (usually decisions that you never even considered) at a moment's notice. Is it important that the stones of the tower are unevenly spaced? Surely, in case someone wants to knock it over. Does it matter that the man you're talking to has a beard? It does if you want to set his face on fire.
These are extreme examples, but it serves to illustrate my point. When someone is reading a novel, those are details that they don't always need right away. They aren't tasked with making any decisions. Novel-reading is interactive, don't get me wrong, but in a writer-reader-tale-construction sort of way, not in an active decisions-making way. You could, for example, reveal the beard later (or casually: "He scratched his beard" is just as legitimate as legitimate a way to show that a man has a beard in a novel as saying it straight out -- whereas, in a D&D game, if you had not previously described the man as having a beard players might be prone to shout "He has a beard?!") and keep the stones of the tower completely out of it (unless it somehow helped to build the scene).
This has been a near-constant struggle in my long-form writing. I'm far too used to giving everyone an immediate description of EVERYTHING, from light-quality to material. I think I've finally managed to conquer the urge, but not without great efforts.
On a lighter note, a friend (Christine Duffy) was once an editor and she is going to see if she can get some folks who are still editors to have a read over the manuscript and see if they maybe want to, you know, publish Heavenly Devices. So you might be looking for it in a bookstore near you sometime soon.
Oh, and Heart of Darkness progresses apace. Jocelyn and I are waiting for all the art to come in so we can lay it out and put it up. Those of you who won yourselves a free copy by reviewing Sordid Stories and the Adventurer's Guide to the Imperial City, you'll still get it. I promise!