e23 has now followed up GURPS Castle Falkenstein with my own GURPS Castle Falkenstein: The Ottoman Empire, which by the way is dual-statted for GURPS and the original Castle Falkenstein rules.
Like most Falkenstein game material, this book entangles a fair amount of authentic 19th century history with a lot of rather gonzo steampunk high fantasy. The difference is that I was working with the history of the last years of the Ottoman Empire, which got rather gonzo in its own right, by most rational standards, as well as being as depressing as a lot of history when you look closely. Ottoman Turkey really was an archetypal totally screwed-up ancient empire on the slide. That makes it an interesting place to visit, but you really wouldn't want to live there.
The book itself is almost interesting in its way, because it follows the original Castle Falkenstein standard presentation style of including a lot of first-person setting fiction. (That's not Steve Jackson Games' house style, but the book was originally written for R.Talsorian. The Designer's Notes explain.) Come to think of it, Ottoman Empire may represent the single largest work of fiction which I've ever had published, interwoven with the games stuff. Which is probably either cool or sad. Very possibly both.
I did have some fun deciding what to put into the "Cinema" section of the bibliography, I must admit.