[hyphz]

I always start worrying about quality control on this kind of game, where the key secrets of the setting are "left up for the GM to discover".

If you, the author, don't know what the secrets are - then how do you know they are cool, or fun, or interesting? If you weren't inspired by one of them to work out a secret and write it in the book, then what basis do you have for expecting your readers - who are not published authors - to do so?