6 books in series

Secrets of the Games

Secrets of the Games is a 6-book series with 6 primary works first released in 1990 with contributions by Rusel DeMaria, Zach Meston, Andrew Eddy, Tom Stratton, and Alex Uttermann.

Sega Genesis Secrets
Nintendo games secrets
Super Mario World Game Secrets: The Unauthorized Edition
Super Metroid Unauthorized Game Secrets
Super NES Games Secrets
The 11th Hour: The Official Strategy Guide