What are the most popular books in the list of 2015 science fiction fantasy books?

I think 'The Grace of Kings' by Ken Liu was also quite popular. It has a great blend of Asian - inspired mythology and science fiction elements. It's about kingdoms and power struggles in a world that has some advanced technological aspects.

The 'Divergent' series was also very popular. People were drawn to its unique concept of the factions in society. The idea of having to choose a path in life based on a certain trait and then dealing with the consequences was really interesting to readers. The action scenes and the development of the relationship between Tris and Four added to its appeal.

Probably 'Ancillary Justice' too. It was praised for its fresh ideas regarding AI and its exploration of different forms of consciousness. The story's scope, spanning across different planets and cultures in a far - flung future, made it stand out among other books in the genre in 2013.

Probably 'The Fifth Season' was quite popular. Its unique take on post - apocalyptic settings and magic made it stand out. People liked the way it explored different cultures within its world.

'Gateway' is also very popular. Its exploration of human nature in the face of the unknown, along with the unique setting of the alien space station, has attracted a large number of readers. People are drawn to the mystery of the ships and the potential for discovery, as well as the well - developed characters.

'Wool' by Hugh Howey was quite popular too. It's set in a post - apocalyptic silo, and the mystery and the characters' struggles within that confined space were really engaging for readers. The story gradually unfolds, revealing more about the world outside the silo as it progresses, which kept readers hooked.

I'm not sure which ones are the most popular exactly, but 'Snow Crash' by Neal Stephenson is often highly regarded. It's set in a future where the world has been transformed by a new form of technology and virtual reality, and it has a really unique and engaging plot.

I'm not entirely sure which ones were the most popular, but 'Doomsday Book' was widely talked about. It had an interesting premise of time - traveling historians.

Another popular one could be 'The Uplift War'. It was part of a well - known series and had a lot of fans who were into the idea of the uplift concept, where lower species are 'uplifted' to sentience by higher ones. It had exciting battles and interesting alien species interactions.

Another popular one might be 'The Uplift War' by David Brin. It's part of a series and in 1989 it was attracting a lot of attention for its unique take on the evolution of intelligent species and the politics between them.