Two words: Feature Creep.
Guns of Infinity was only supposed to be about 100k words long, if you believe it. The first act actually conformed to that pretty well, but as the story went on, more and more branches and consequences led to more and more case results which demanded more and more paths. In addition, I was also soliciting feedback from the fans, and a good chunk of that feedback was “why can’t I do ”. While a lot of these requests were unrealistic or had perfectly good Watsonian reasons for not being implemented, a lot of them didn’t, that not only meant more words for options, but also more add-on consequences for those decisions later down the line, just to make sure the players know their decisions had long-term results.
Add to that the fact that Guns of Infinity was a sequel which had to account for all the consequences of major decisions made in Sabres of Infinity, and 440k words is really what I should have expected. At this point, I’m expecting Lords of Infinity to easily break 500k words, though I’m also killing enough characters and burning enough cities to the ground making plans to ensure that War of Infinity and Masters of Infinity don’t balloon too far past that.