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.
I decided to rig him up to a doomsday switch. I was digging deeply at the time and knew it was a matter of time since I was digging aggressively and had a small army. As it turns out a single beast from the candy depths crawled out of a crack in the rock and moved quickly, it scuttled through the mines and through a modest barracks, my dwarves were ill prepared and with the miners and soldiers dead, the lever was pulled. Ewiwi waited patiently on the surface, apparently enjoying the screams of his captors from below which lasted for some time. While poor on physical defence the fort was rich in terribly optimized pathways ensuring a slow and arduous escape for the monster below. Eventually the beast from below exited the fort, gave a gentlemanly nod to Ewiwi, and left east.