My cousin has a kickstarter going for a tabletop setting that will allow players to easily blend characters and gear from any d20 source book into one genre-bending time space continuum fracturing mega-adventure.
https://www.kickstarter.com/projects/163020356/timeline-fracture
ooo
So if I understood this right, he wants to make a book that serves as a medium between the other books in terms of rules and such?