Depends if we are counting hours/days played or just when we first startede playing the game/series of games.
WoW: around 200 days playtime since '06
I started out playing "Doom 3d" in 1995 and I have finnished all the games in the series. Doom 3 came out in '04, Doom 4 was annouced in '08 so it's long over due imo.
I have also finnished all of the "Age of Empires" games.