I think 'Ender's Game' by Orson Scott Card is very popular. It tells the story of a young boy, Ender, who is trained to fight in a future war against an alien race. The moral and ethical questions it raises are quite fascinating.
In the list, 'The War of the Worlds' by H.G. Wells is a well - known and popular one. It was one of the first to depict an alien invasion in a very vivid and terrifying way. Wells' description of the Martians and their technology was way ahead of its time, and it still has the power to scare and intrigue readers today.
In the list, '1984' is highly popular. It has influenced a lot of other works with its themes of surveillance and totalitarianism. Also, 'Ender's Game' is well - loved. The character of Ender and the moral and strategic dilemmas he faces are very engaging.
I think 'Starship Troopers' is quite popular. It has an interesting take on military in a science - fiction setting. The bugs that the soldiers fight are really cool and unique enemies.
'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.
I'm not sure which were the most popular exactly, but 'The Graveyard Book' was widely loved. It won the Newbery Medal. Its blend of fantasy and science fiction elements, along with its engaging characters, made it a hit.
A very popular one is 'Brave New World' by Aldous Huxley. This book presents a future society where people are genetically engineered and conditioned from birth to fit into a specific caste system. It's a thought - provoking look at the potential consequences of scientific and technological advancements on human nature and society. There are many interesting discussions around topics like happiness, freedom, and individuality in the context of this fictional world.