Hello everyone

A good friend of mine is an avid rpg collector and player.

He has many rpg codexes  (even writes his own) and I'd like to get him an uncommon or rare book. Not a collectors item rare sort of thing--just something non mainstream that has a fun theme and interesting ideas. If it's fun, all the better. Not limited to any genre.

Just looking for auto clicker pointers on what search terms  I should start with. If you have an uncommon book, please let me know.

Thanks

What kind of stuff does he like, and what kind of stuff is he likely to own already?

Something pretty original (and a very good game!) is Dialect (https://thornygames.com/pages/dialect). Another, even weirder, is this card-based LARP that is very... David Lynch-y: https://www.indiepressrevolution.com/xcart/Something-Is-Wrong-Here.html.