A cool idea, in concept... but we couldn't get it to work for us. The idea is that you've got a bunch of interlinked rooms... and monsters in a different part of the level will open and close connecting doors, seemingly at random. If it works, it's pretty cool... you'll never know if that grenade you shoot is gonna blow up in your face as the door closes. In practice, we only had a couple of doors open and close for us...