Wow, I can't believe i actually spent over 45 mins to read this whole thread
What i might add is that some games are just incredible, I am a very versatile gamer and switch my game type very often, I get into streaks and play many different games from a category, but there are always some amazing games that have an x-factor that gets me addicted (For example Diablo2 at its time, Counter-Strike when i'm into FPS, WoW in MMO streak, Lords of War and Money when i play browser-based games and last but not least KB:L at TBS phase)
Usually I get bored of a game once I know the whole storyline (even tho I didnt finish every quest or found every kind of mob or found out every unique stuff), It simply gets dull and thanks to that game i abandon the whole game-type, until I remember those great games from the respective type with the x-factor and I start playing them again, so I dump the current type and re-embrace one from the past.
A few games that marked me and made me spend countless hours in front of the computer are Fallout 2, M&M series, some old games (such as Baldur's Gate that i still play from time to time), Planescape: Torment, numerous shooters, Diablo series, Spellforce, and a few other but the names are slipping.
PS: I want to apologize because i use so large posts to express my thoughts and opinions