Zorg explains the lure of World of Warcraft, from levels and quests to chains and night elves.
WoW-ers can spend days glued to the computer, and it's difficult to interrupt a Wow-er when one moment of inattention means that his/her character could be toasted by a dragon, squashed by a troll, or otherwise reduced to "ghost" status. However, the game does allow breaks, in which a player retreats to a safe area in the game, such as an inn.
A polite way to get a WoW-er to disengage is to say "You have 10 minutes to find an inn." If that doesn't work, I suppose you could call Rent-a-Dragon.