At this point in time, it is not as unusual for me to come across stories that have a chronological order and a release order. That said, no matter how many times we've reworked or rearranged things since we first began writing, we have always started Grims' Truth in Nex after the abduction of the High Queen's successor.
Originally, each arc was a single book. When we signed with Evolved Publishing we redesigned the series into three books per arc, twenty arcs, with a sixty book plan.
In the past, beta readers have frequently asked: What's the purpose of having a release order and a chronological order?
a) The release order starts the story at a point where the main character has a level of understanding that is close to the reader. The Universe, Euphoria, is very broad with many facets, laws, and rules that take time to learn and understand.
b) Time is not linear. The characters travel through space and time, so it important to understand how and why they might not be privy to certain information.
c) It's more interesting. To be blunt, it's more interesting not to have all the answers straight out of the gates. The mystery is half the fun and it makes the books more compelling when readers read through them again later with new-found knowledge.
As you can see in the release order, we did write a novella called the Dead Queen, which is Book 0. This book used to be available through our newsletter and we suspect that it will be edited in the future for this purpose but, as of now, it is unavailable.
I omitted the book names for the events listed above because we want to keep some secrets this early in the story! Though, through some general chatting with Yin and I, we would say all of the early GT answers that readers are usually looking for come around Arcs 4 and 5.
We're being pretty open with readers these days because we have some who have been following and supporting us since we first began this project eight years ago.