onarliog: No Man's S... screw it, I can't even finish the joke.
I'd say Populous in 1989. A revolutionary game that nobody quite understood on release, only to spawn a hugely popular genre of its own in the following years.
EDIT: Dammit, forgot about the "PC" part.
It's in the list I linked to but if you have anything to add, that'd be cool.
dtgreene: From what I have read, Ultima 9. Apparently, its over-the-shoulder camera hadn't been done before, and even the system requirements were ahead of its time (which, of course, makes the game inaccessible to many players).
Of course, being ahead of its time doesn't actually make the game good, but then again, I haven't played it (the lack of a female Avatar option in Ultimas 8 and 9 is a dealbreaker for me).
For an RPG perhaps? But Tomb Raider was from 1996, soon followed by Mario 64 and there were a bunch of games like them in the following years. There's also I, Robot from 1983 (!), and Alpha Waves from 1990.
You might have use for this list then:
http://www.mobygames.com/game-group/protagonist-female