Strangely enough, given my previous post, it’d be a Fighting Fantasy book. I strongly remember it being Ian Livingstone, but not what book it was.
Going back to the idea of proper RPGs, it’s a little trickier. I’m not sure which I bought first – Orpheus or Witchcraft.
I suspect it was Orpheus, as Witchcraft was out of print, and I had to order it from America. Admittedly, that may still mean I bought Witchcraft first, but Orpheus was almost certainly in my hands first.
I now own all of Orpheus, including the short stories book. It’s one of the only games I own in its entirety – may in fact be the only game. I’ve only skimmed some of the later books in the vain hope that someday I might get to play in a proper campaign and knowing all the metaplot would spoil things a bit.