Its no mystery that massively multiplayer online games (MMOs) in general are arguably the greatest (or worst, depending on perspective) time-sink in the gaming world. The public's concern regarding this led to the various developers putting tips on splash or loading screens reminding players to take a break every once in a while. So then, is it a new design paradigm or a design flaw that led to the creation of an encounter in one of these games that can last for over 18 hours? In Square Enix's "Final Fantasy XI", there exists a boss encounter called 'Pandemonium Warden'. A few days ago, a group of players from the Link-Shell (that game's version of a Guild) BeyondTheLimitation attempted to defeat this encounter. One (or possibly the only) attempt lasted for 18 real world hours. At the end of this time, the attempt was ended not because the boss was defeated, or because the player characters died, but because, "People were passing out and getting physically ill. We decided to end it before we risked turning into a horrible new story about how video games ruin people's lives."
The MMOG community site www.massively.com has a more in depth article on this subject here.