'Rendezvous with Rama' by Arthur C. Clarke is another popular one. It presents an encounter with an alien spacecraft, Rama. The detailed descriptions of the huge, mysterious Rama and the speculations about its purpose and the beings that created it fascinated many readers.
Definitely 'Ender's Game'. It has a huge fan base. People are drawn to the character of Ender and the intense battles he faces, as well as the moral questions about using children in warfare, even in a fictional future military scenario.
I think 'The Martian' was extremely popular. It was widely praised for its scientific accuracy and the engaging performance of Matt Damon. People were really drawn to the idea of a man alone on Mars trying to find a way back home.
'Contact' by Carl Sagan was also very popular. It was a thought - provoking story about the search for extraterrestrial intelligence. The movie adaptation also helped to boost its popularity. It delved into scientific concepts as well as human emotions when faced with the possibility of first contact.
'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.
Among the popular ones is 'Starship Troopers'. It's a military science fiction novel that has an exciting story. The audiobook has great sound effects and a good narrator that really makes you feel like you're in the middle of the action, following the soldiers in their battles against the alien bugs.
'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.