Lots of people like to reminisce about the first RPG they either owned or played and understandably so. That's a foundational experience that, in my opinion, sets the tone for one's later involvement with the hobby. But what I'm curious about today is everyone's second RPG, the one they bought or played after their initial introduction into the hobby. Just as important is why you bought or played that second RPG.
My second RPG was Gamma World, which I bought likely on the strength of the references to it in the Dungeon Masters Guide, the fact that it was sold in stores right next to D&D, and was produced by TSR. That it was a post-apocalyptic game probably helped, too, since I was a big fan of movies like Planet of the Apes and Logan's Run.
So, what was your second RPG and why?