Ian Millington's GM-less, collaborative RPG called Ergo, in book form. He wrote this back in 1999, but got busy with his other career(s), so his plans to release "a final version" never came to fruition.
The original website hosting Ergo is no longer, but thanks to archive.org, it is still available.
I augmented the original material with some additional stuff on the subject from Ian, and turned it into a LaTeX document. I thought this was a cool result, so I asked Ian for permission to share it on GitHub. He replied
Wow, thanks Dylan. This is absolutely fine. I'm very happy for you to share the content in this way.
I hope you have fun with it!
And I now hope you do too.
In addition, I used my own program, Cheap Impostor, to create an "imposed" version of the book, ready to print duplex (with short-edge binding), and each sheet folded in half, and the folded edges glued to make a proper book. I think it works out quite nicely. I made versions for letter- and A4-sized paper.