Or you can just make a credits mode, where the game skips directly to the end credits so you don't have to put in any effort at all. I think what you're looking for, is a book. But then, that'd require reading...hmm, that's difficult for some. So maybe a book with footnotes? I mean, it still requires reading, but it gives you the gist of it.
Nah man, too much effort. I would like to put forward the "Participation Sticker", in which paying the price for Bloodborne lands you a sticker that reads "I beat Bloodborne"