Can you recommend some best free science fiction novels?

Sure. 'The Hitchhiker's Guide to the Galaxy' by Douglas Adams is a very popular free science fiction book. It's full of humor and absurd situations as it follows the adventures of Arthur Dent through the galaxy. Another is 'I, Robot' by Isaac Asimov. It's a collection of short stories that deal with the relationship between humans and robots. And 'Rendezvous with Rama' by Arthur C. Clarke is a great read. It's about an alien spaceship that enters our solar system.

Sure. 'Starship Troopers' by Robert A. Heinlein is a great one. It explores military life in a science - fictional universe. Then there's 'A Canticle for Leibowitz' by Walter M. Miller Jr., which is set in a post - apocalyptic world with a strong religious undertone. 'Slaughterhouse - Five' by Kurt Vonnegut also has science - fiction elements and is a unique take on time and war.

Definitely. 'Alif the Unseen' is a wonderful 2013 science fiction novel that blends different elements well. 'The Golem and the Jinni' is a great read. It creates a vivid world with its mythical creatures. 'Zone One' is a great zombie - related science fiction novel from 2013 that offers a fresh perspective on the genre.

One of the great 2018 science fiction novels is 'The Calculating Stars' by Mary Robinette Kowal. It's set in an alternate history where a meteorite hits the Earth, and it focuses on a female pilot's fight for equality in the space race. Another is 'Record of a Spaceborn Few' by Becky Chambers. It explores the lives of ordinary people living in a vast galactic community. And 'Annihilation' by Jeff VanderMeer is also notable. It takes readers on a strange and mysterious journey into Area X, a place full of odd and dangerous phenomena.

I would also recommend 'Hyperion' by Dan Simmons. It has a frame - story structure where different characters tell their own tales on a pilgrimage to the Time Tombs on the planet Hyperion. The stories are diverse, ranging from a soldier's love story to a scholar's encounter with an alien intelligence, and the overall mystery of the Shrike is very engaging.

A great one is 'Ender's Game' by Orson Scott Card. It follows the story of Ender Wiggin, a child prodigy trained to fight in a future war against an alien race. It explores themes of leadership, morality, and the cost of war.

One of the best free science fiction novels is 'The Time Machine' by H.G. Wells. It's a classic that takes readers on a journey to the far future. Another great one is 'Frankenstein' which can be found for free in some e - book libraries. It explores themes of creation and ethics in a science - fiction context. And '20,000 Leagues Under the Sea' by Jules Verne is also excellent. It offers an exciting adventure beneath the ocean waves.

Then there's 'This is How You Lose the Time War' by Amal El - Mohtar and Max Gladstone. Two agents from opposing factions in a time war communicate through letters hidden in different time periods. Their relationship evolves from enmity to something much deeper, a love that defies the very fabric of the war they are in. It's a beautifully written novella that combines time - traveling concepts with a very unique and tender love story.

Sure. 'Frankenstein' is a must - read. It was one of the first novels to really explore the idea of artificial life. Then there's 'The Invisible Man' by H.G. Wells. It's a really cool concept about a man who becomes invisible and the problems that come with it. 'Around the World in Eighty Days' by Jules Verne is also a great early science fiction novel. It shows an adventurous journey around the world with the help of modern technology at that time.

Sure. 'The Caves of Steel' by Isaac Asimov. It's a great detective story set in a future where humans and robots coexist in a somewhat tense relationship. Asimov's masterful writing makes the world and the characters, both human and robotic, very engaging.