Stealing from Aaron de Orive, my first ten tabletop RPGs in ten days, in the order in which I encountered them. You might expect my first to have been the then-ubiquitous AD&D--the Windows 95 of roleplaying!--but it was not. Instead, it was John M. Ford's science fantasy Starquest, an extremely simple, four characteristic, class-based RPG that as far as I know was only ever published once, in the pages of the July 1979 Asimov's. It didn't have a cover as such but it did have a George Barr illustration.
Like most good-hearted people, I preferred well delineated borders between my SF and F. This "role-playing" sounded pretty silly to me. I didn't expect the idea to thrive and I certainly did not foresee spending time on it.