This book is the second best action book I have ever read (the first one being Skymaze, the sequel by the same author). I loved this book, and I loved the game that Rubinstein created. Space Demons should be made into a real game if you ask me (who knows, I might even take matters into my own hands someday when I have big enough hands!). The characters were great. I loved the way Mario would always bumble into a situation and not take anything seriously. There was, however, a big flaw in the design of the book. When they were in the game, it didn't say enough about what happened in there, how it felt, or exactly how the Space Demons looked like. I always thought that the demons were just black blobs with glowing eyes and horns. If it hadn't been for the cover, I would have never known these things. Other than that, I would like to suggest that you rent the book first, but you will probably end up buying the book anyway. Gotta go, some big black blob is in my room