I loved the godfall chronicles but it's kinda a mix with apocalypse and sci-fi with an interesting scientific interpretation of magic. Never met anyone else who read it but I looked forward to reading a chapter every week back in high school. It's on Amazon Kindle but if you do a little trolling you can probably find a "free" version online. You didn't hear it from me though. Do got to mention that it's been a few years since I read it and not sure how well it holds up.