Oblivion was my first. October 24, 2008 is the day I discovered Oblivion.
I bored one night, and was wondering if there were any new games out for the PS3. I didn't actually own a PS3 at that moment, but I figured if there were any cool games out, I would buy one of these. I had some money saved. So I went on gamerevolution.com and went through all the PS3 games which were out at that moment, starting with the letter A. Assassin's Creed was not out at that moment; if it had been, I probably would have gotten that game.
I wound up going through most of the alphabet (A.. B....C ... D.. ) until I got to T. I started to read the article which features The Elder Scrolls:IV Oblivion, STARTED, that's the key word here. I only got maybe halfway through this article before closing the Internet grabbing my keys, and literally driving to a local mall, buying a PS3, and this game I'd never heard of.
TES: 4 promised several things I had been looking for since the 1980s: large, open world without persistent barriers (a lot of PS2-era RPGs are linear), a medieval setting, and one which seems inspired by DnD. I also wanted a game which actually lets the player create any sort of character they want: male OR female. Once I discovered Oblivion, I was instantly hooked. I called in 'sick' the next day to work.
I grew up with pen 'n' paper games, and even back then, I figured that someday, somebody would create a game which features all the stuff I imagined during combat, and even peacetime, without the dice rolls, and so there ya have it.