I played Oblivion religiously back when it first came out. I haven't played Skyrim yet and I doubt I'll have the time for it.
However, Modern Warfare 3 is all I play now next to NCAA 2013. Someone mentioned Age of Empires...wow that took me back... Most addictive game next to Starcraft. I'm a pretty open gamer, from being in Madden/ NCAA Football tournaments to Metal Gear and Halo.