Oblivion. Released over 2 years ago, it's still talked about daily. A game that is surprisingly addicting, and a game that you just can't stow away on the shelf. THis is made surprising due to the game's lack of any online play abilities whatsoever.
Mario. Started on old nintendo consoles that can now be found in antique shops, it's a series that just doesn't seem to die out.
GTA. Started in the early '90s, and a major turning point in bringing video games out of the almighty grasp of the censorsship bureau, it is long lived, and a virtual revolutionary.
Battle field series. For a game whose concept and style never changed throughout the years, Battlefield has held it's spot in the top-selling video games since 2001.