From the PDF's Introduction:
Adventure any where, any time. It sounds like a recipe for endless vacation right? It would be if not for all the crazies that want to undo the universe from either end. Nope, having your own time machine comes with a lot of responsibility. The heroes were chosen by chance, fate or some higher order to step outside the ordinary flow of time, to see a wider vista than others were ever meant to see. They may do it reluctantly or without understanding their purpose in the beginning, but when they're charged with shepherding the entire universe, eventually the will heed the call or everything might just cease to be. It's their choice. With the whole of creation before them, it could be difficult to decide what to do. Sometimes they will find clues that they will want to check out later, but often adventure finds them no matter where they are. That is just the nature of being a hero.