Large cast of characters (my favorite or most interested in is Ingrid. She is first pointed out as being you know crazy but I immediately thought there's got to be something deeper with her)

complex world building (it does take a bit to get into the book. There are two timelines so you get backstory while being sent to the "here and now" often) 

unique storyline (who didn't love a scavenger hunt? 
( I have always wanted to do one as an adult and one that was done in one era and reinstated in another era, this time with technology at the hands of anyone who wanted to participate?... That's pretty cool)

The author's note at the beginning of the book is very important to the story so make sure that you read it!

Honestly, I DNFd this. I read some of it though