one of my favorite things I learned a few years back was the
   "Doorway effect".* The answer to "Why do I forget things when I
   go through a doorway?"* I always thought since then that there
   is some significance in gaming and doors/portals/etc.* Well, I
   found a great article about game design theory on the very
   subject... and I love that it goes through the history of
   gaming, from Zork on upwards.
   http://www.gamasutra.com/view/feature/193943/what_lies_beyond_doorways_in_.php?print=1