Tes IV: Oblivion I played the game over 600 hours on my laptop and over 1000 hours on my ps3. I have done everything you can do in Oblivion and it is the most epic RPG game to date
I can't even begin to explain how much I've customized this game after exploring every rock, every mushroom, I created mansions in the mountains, temples in the skies, cities in the forests, you name it. I've made rings that let me fly, and me and my best friends used to even make quests for each other to figure out. I've never got stuck in a game like I have Morrowind, it's probably a problem but I don't care. I love this game.
Its a toss up between Elder Scrolls: Oblivion and the Legacy of Kain series..... I'd say LoK purely because I have been playing it for the last 8 years and am still not bored of it. It has some epic replay value to it.