Allright, this probably sounds a little cliche', but i will say it anyways. Metal Gear Solid. This game is one of my all time favorites for many reasons. The innovative gameplay, the revolutionary graphics(at the time
), and character development.
For me, until MGS, i was used to the platformer games that had no real story and you just bounced around from level to level in a mindless existence. MGS made me think, strategise, and made me want to play over and over again. I hope this is the kind of stuff that you were looking for, this is just my opinion to all you snake haters out there!