Apparently Guinness has put a "Top 50 Games of All Time" list in its Guinness World Records Gamer's Edition 2009 book. It's conspicuously console-heavy and focused on recent titles, with familiar faces including BioShock (#40), Star Wars: Knights of the Old Republic (#41), and The Elder Scrolls IV: Oblivion (#46).
It's stated that the games "were ranked on their initial impact, lasting legacy, how fun they were to play". If that's a fact, I'm seriously missing quite a few titles.