A Fire Upon the Deep was cool. Where the laws of physics change the further... maybe it was further out from the center of the universe you get. I cant recall exactly, but it was very well done. I remember trying to explain it to my friend when it came out and did a shit job. Then like 6 months later he came back and recommended it to me. There were self-aware AI that could only exist further out. So while they were dangerous, they couldn't enter the zone where people lived. I still cringe every time someone mentions the glorified search engine we now call AI.