It depends on your definition of "gaming."
Riven is what got me really interested in games in the first place. I'd always been more into books when I was a kid, because I thought video games were just violent, ugly-looking, and uninspiring "guy" stuff, like Mortal Kombat.
I was 11 when Riven came out. My dad picked it up, since he enjoyed Myst, and I became obsessed with watching him play it. I was too much of an idiot to be able to contribute to his playing, but I couldn't get enough of the world it was set in. It's the whole reason I started worldbuilding and conlanging, which have been favorite hobbies of mine ever since.
I didn't get into games in a serious way until early 2006, when some gamer friends convinced me to start playing Final Fantasy XI. Again, it was the world that I fell in love with. From that point on, encouraged at first by said gamer friends, I became more and more of a gamer myself, though I wouldn't have used that term to describe myself until about a year ago when I moved in with someone who owned an Xbox 360, a PS3, an enormous game library, and a nearly bottomless wallet when it came to Christmas/birthday gifts for me. At that point I could begin to experience a wider variety of games than I'd had access to previously and feel like I qualified as a "gamer."
So yeah, Riven in 1997 and then FFXI in 2006.
Of course, I'm still more into artsy, puzzle-y, exploration-based games than anything else, and generally on the PC just because it always seems to work out that way.