While it may not be my favorite as such, the book that started me back to gaming (and even more amazing, GMing) after a decade or so was Perpetrated Press's Arsenal book. It was the first gaming book that I had ever read (including Mage and Shadowrun) that treated Techno Magic properly, as advances in MAGIC and magic items, NOT just adding magic to technological devices. The companion book Factory was just as good. I was VERY sorry to see them disappear. I still have hopes that they decide to publish the rumored and unfinished third book someday as a PDF, or hand it off to one of the other excellent pdf publushers such as Ronin Arts, E.N. publishing, CWG, etc.
skippy
GM of the Cursed Earth Campaign