The term 'long gone novel' is rather ambiguous. It could be a novel that was written a long time ago and is no longer in print or widely read. Maybe it's a story from a bygone era that had unique themes or writing styles that are no longer common. Without more context, it's hard to say exactly what it's about.
The story length of Days Gone varies depending on how much side content you explore. But on average, it takes around 30-40 hours to complete the main storyline.