There was a time when the Blizzard parking lot used to empty out before 11PM - but that was before the internal alpha of World of Warcraft went live. Although the population of the Blizzard building isn't quite enough to make for a truly "massively" multiplayer experience yet, somehow the call of exploring Azeroth and Kalimdor, even with fifty of your office mates, is enough to override more sensible instincts like eating and sleeping.