First Contact, exploration of consciousness, sentience/intelligence (and their relationship), Transhumanism, Hard Sci-fi, not challenging but it will not hold your hand through the book.

I would be remiss if I didn't mention the book has vampires, but explored in a reality where vampires are an extinct offshoot of homosapiens, resurrected for specific purpose. The explanation of vampires is fascinating, grounded in evolution and actually... believable? This is not a vampire book at all but their presence is not only plausible, it's core to the themes of the book. Highly recommended.