Our rankings are cleverly generated from the algorithmic analysis of thousands of customer reviews about products, brands, merchant's customer service levels, popularity trends, and more. The rankings reflect our opinion and should be a good starting point for shopping. As an Amazon Associate we may earn from qualifying purchases. We may receive a commission from purchases made through links on our site, which will help us continue to provide you with value.
Best Choice 
The Receiver: A Hard Sci-Fi First Contact Techno-Thriller Best Value The Receiver: A Hard Sci-Fi First Contact Techno-Thriller Audible 
Extinction: A Military Sci-Fi Thriller: Extinction, Book 1 Audible Extinction: A Military Sci-Fi Thriller: Extinction, Book 1 
The Somatic Bridge: Gripping New Hard Sci-Fi Adventure. (Expansion Book 1) Audible 
The Final Stand: A Colonial Fleet Novel: Nexus House, Book 1 Audible 
The Final Stand: A Colonial Fleet Novel: Nexus House, Book 1 Descartes' Shadow: A Metaphysical Hard Sci-fi AI Technothriller Descartes' Shadow: A Metaphysical Hard Sci-fi AI Technothriller Pygmalion Media Generations: A Science Fiction Mystery Thriller Pygmalion Media Generations: A Science Fiction Mystery Thriller scifi-thriller.com Reactor: Science Fiction Thriller scifi-thriller.com Reactor: Science Fiction Thriller Final Contact (Two Complete Series) Final Contact (Two Complete Series) The Object: Hard Science Fiction The Object: Hard Science Fiction Contact: Echoes in the Dark: Hard Science Fiction Contact: Echoes in the Dark: Hard Science Fiction Independently published Where Water Learns to Stay: A Hard Science Fiction Novel of Lunar Permanence Stunning Short Stories of Fantasy and Science Fiction: Superb Collection of Speculative Fiction Second Sky Starship Salvager: An action-packed military space opera (Paragon Space Book 1) Second Sky Starship Salvager: An action-packed military space opera (Paragon Space Book 1) Uphill Downhill Press, LLC Wine Dark Deep: A Hard Science Fiction Space Opera - Book One: 1 Hard-SF.com The Enceladus Mission: Hard Science Fiction (Ice Moon Book 1) Hard-SF.com The Enceladus Mission: Hard Science Fiction (Ice Moon Book 1) A7L Thrilling Books Limited The Genesis Signal: Science Fiction Thriller A7L Thrilling Books Limited The Genesis Signal: Science Fiction Thriller Exemplar: Hard Science Fiction: The Autonomous Sequence (Book 1) Exemplar: Hard Science Fiction: The Autonomous Sequence (Book 1) Xenophile Press Oblivion Threshold: A Military Science Fiction Space Opera Epic (The Oblivion Saga Book 1) Nexus: A Science-Fiction Thriller Nexus: A Science-Fiction Thriller The Darkness Between the Stars (First Contact) The Darkness Between the Stars (First Contact) The Wooden Pen Press Venusian Uprising - A Military Hard Science Fiction Epic (Aeon 14: The Sol Dissolution Book 1) The Wooden Pen Press Venusian Uprising - A Military Hard Science Fiction Epic (Aeon 14: The Sol Dissolution Book 1) The Darkness Between the Stars (First Contact) The Darkness Between the Stars (First Contact) Hard-SF.com The Dead Planet: Hard Science Fiction (The Marchenko Logfiles Book 4) Hard-SF.com The Dead Planet: Hard Science Fiction (The Marchenko Logfiles Book 4) Hard-SF.com The Atacama Incident: Hard Science Fiction Hard-SF.com The Atacama Incident: Hard Science Fiction Quartermaster Press Darwin's Dilemma: A Metaphysical Hard Sci-fi AI Technothriller Quartermaster Press Darwin's Dilemma: A Metaphysical Hard Sci-fi AI Technothriller Hard-SF.com The Luna Monolith: Hard Science Fiction (The Black Monolith Book 1) Hard-SF.com The Luna Monolith: Hard Science Fiction (The Black Monolith Book 1) Ghosts (First Contact) Ghosts (First Contact) Next Chapter Displaced TOR.com All Systems Red: The Murderbot Diaries Hard-SF.com The Torn Planet: Hard Science Fiction (The Marchenko Logfiles Book 1) Hard-SF.com The Torn Planet: Hard Science Fiction (The Marchenko Logfiles Book 1) M.L. Knaggs Shard Awakening (The Shard Legacy Book 1) M.L. Knaggs Shard Awakening (The Shard Legacy Book 1) Green Hill Publishing Homo Machina: A Post-Apocalyptic Hard Sci-fi Genetic Engineering Thriller Green Hill Publishing Homo Machina: A Post-Apocalyptic Hard Sci-fi Genetic Engineering Thriller Audible Silent Sun: Hard Science Fiction Audible Silent Sun: Hard Science Fiction The Shackleton Signal: Hard SF Thriller The Shackleton Signal: Hard SF Thriller Galactic Spacetime Publishing Time is not Enough: A Science Fiction Spy Thriller Galactic Spacetime Publishing Time is not Enough: A Science Fiction Spy Thriller Hard-SF.com The Disturbance: Hard Science Fiction Hard-SF.com The Disturbance: Hard Science Fiction Hard-SF.com Mars Nation 1: Hard Science Fiction (Mars Trilogy) Hard-SF.com Mars Nation 1: Hard Science Fiction (Mars Trilogy) Futureword Publishing Blue SunRise: A Riveting Character-driven Hard Sci-fi Adventure (Blue Sun Space Opera Book 1) Futureword Publishing Blue SunRise: A Riveting Character-driven Hard Sci-fi Adventure (Blue Sun Space Opera Book 1) Primordial Press Freedom's Last Gasp: A Hard Science Fiction Thriller (The Exodus Series Book 2) Primordial Press Freedom's Last Gasp: A Hard Science Fiction Thriller (The Exodus Series Book 2) The Children of Ishtar: A Frontier Conflict Chronicle July 2297 - September 2297 (The Frontier Conflict Saga Book 4) The Children of Ishtar: A Frontier Conflict Chronicle July 2297 - September 2297 (The Frontier Conflict Saga Book 4) The Children of Ishtar: A Frontier Conflict Chronicle July 2297 - September 2297 (The Frontier Conflict Saga Book 4) The Children of Ishtar: A Frontier Conflict Chronicle July 2297 - September 2297 (The Frontier Conflict Saga Book 4) Cosmic Entanglement Media The Foundry: A Hard-Science Fiction Space Opera (Book 1) Cosmic Entanglement Media The Foundry: A Hard-Science Fiction Space Opera (Book 1) Hard-SF.com The Hole: Hard Science Fiction (Solar System Series Book 1) Hard-SF.com The Hole: Hard Science Fiction (Solar System Series Book 1) J Triptych Publishing Visitor: A Hard Sci Fi Thriller (Transcendence Book 1) J Triptych Publishing Visitor: A Hard Sci Fi Thriller (Transcendence Book 1) Kaye Klub Publishing Unbreak Him Kaye Klub Publishing Unbreak Him The Mars Anomaly: Hard Science Fiction The Mars Anomaly: Hard Science Fiction Hard-SF.com The Krill Enigma: Hard Science Fiction Hard-SF.com The Krill Enigma: Hard Science Fiction Audible The Triton Disaster: Hard Science Fiction (Solar System Series, Book 4) Audible The Triton Disaster: Hard Science Fiction (Solar System Series, Book 4) Flight of the Denali: A Frontier Conflict Chronicle November 2296 - April 2297 (The Frontier Conflict Saga Book 1) Flight of the Denali: A Frontier Conflict Chronicle November 2296 - April 2297 (The Frontier Conflict Saga Book 1) AS1 AS1 Uksak E-Books Die Kriege der Galaxis: Zehn Science Fiction Abenteuer (German Edition) Neon Horizon - Books 1 - 3 Box Set: A Cyberpunk Thriller (Neon Horizon - The Complete Series) AS1 AS1 Primordial Press Primordial Threat: A Hard Science Fiction Thriller (The Exodus Series Book 1) Primordial Press Primordial Threat: A Hard Science Fiction Thriller (The Exodus Series Book 1) Hard-SF.com The Clouds of Venus: Hard Science Fiction (Solar System Series Book 5)