This was the first Rifts Sourcebook, and it is still my favorite. This revised & expanded version is even better than the original.

There are a lot of new ideas brought forth in this book. Archie 3, the Shemarrian tribes, new equipment from Flying Titan industries and others. The best part is the section on Robot/AI player characters.

The book is also graced with a large selection of very fine art that fits the mood of the setting perfectly.