This is a wonderful suggestion, and it would be the best use of Gatan material as presented in OQ2 if it's not to be expanded upon in the foreseeable future. A sixty-four page long gazetteer would make the core rulebook much heavier than it needs to be, while twenty - thirty pages don't offer enough meat to serve as a campaign setting. But those same twenty pages would serve as an excellent example in a book on worldbuilding. I agree that it's vital to keep the project managable. Some polish, slight changes and revisions, new artwork and improved layout, all of this is already something that makes a great game even better. But it would be great to hear about a vision for the product line, even if it's stretched over the next decade. I'm pretty sure that I will still be playing OQ those ten years from now. The 20/40 modifier rule is already something I use at the table. Simple math is something that sits well with the idea of OQ being a simple system.
I love the refreshed edition. The Gatan setting material deserves it's own book, and keeping the page count below 200 was a great decision. For me, OpenQuest is a game I run when I feel Mythras is too much for me and my players. That's why I voted for Option 1. But the best scenario that I could envision would be updating the current version of the rules with new 6x9 layout and new B&W artwork (Jakob is spot on saying the B&W layout of Crypts & Things looks excellent). The book would likely be around 250-280 pages long, and available in hardcover. This re-refreshed edition could be followed by a Empire of Gatan setting book, refreshed digest editions of Savage North and Crucible of Dragons (the latter being my absolute favorite) and an OpenQuest Companion book containing new gameplay systems you could bolt onto the core game if you need extra crunch. This would keep the game at an entry level of complexity, with the Companion being a toolkit covering the whole spectrum between OQ and Mythras. Some other books I would love to see down the line: - Adventures in Pherae - a set of published adventures to go with Crucible of Dragons - OpenQuest: Mythic Earth Companion - guidelines on using Mythic Rome, Mythic Constantinople and Mythic Britain with OQ (or just Non Semper Erit Aestas expanded into a full setting book)