Hey all,
Crucify me if you like, I was the one who made the decision to do the Great City as an OGL product. Work on the Great City project long before 4e was announced and it was designed with 3.5 rules in mind.
That said, anyone familiar with Mario's past work can tell you, he puts the stats in the back of his projects, not wired into the body of the work.
And his maps are just killer. Maps have no system, and three-dimensional maps of an entire city? I can't wait for my copy.
As far as the writing goes, the bulk of the text really centers on describing the City, locations on the map, and details the types of inhabitants, politics, culture, and types of adventures one can expect to find there. So really, with the exception of the chapters on NPC stats and the Bestiary, the rest of it is pretty systems neutral. In the foreward I mention how into the old Flying Buffalo stuff I am, which was all pretty much systems neutral, and I really tried to keep the Great City with a similar design feel. The text was geared towards supporting maps and creating a real mood to the city more than supporting any particular system. On that note, I'd also be curious as to who might be interested in a systems neutral version of the book as well.
Since we're working out a pretty cool series of adventures, I'm also curious to find out what people think would think about the possibilities of systems neutral adventures. It winds up being a little more effort on the part of a GM to be sure, but I'm growing pretty partial to the idea. Thoughts, comments, and suggestions welcome...
Tim Hitchcock