This is the Tenth Anniversary Edition of the RECG complete with a restoration of the original text. Includes the three introductions used (or proposed) in previous editions, plus a new one. 

The Generator itself is a table-based random monster generator designed to create quite unusual, but usable, monsters for your game. It was originally self-published in early 2008, and then picked up for a more professional edition by Goodman Games at the end of 2008. And then years later, it has come home for an ever fancier edition with all-new artwork and a new layout.