Something just caught my eye as I was looking over the pictures on the HHN Media Site. The picture of a room in the parade building you can see a railing going slightly upwards/downwards, depends on how to look at it, and the they is suppose to be the vortex in this house. Well I'm guessing that that railing is above a ramp, that will lead u out of or into the vortex. Also, if you look at the maps it goes 15, 16, and then a map of probally 17, but I can't see the exact picture on it. Anyways, so possibly you could be entering the room or a continuation of a room to the right of 15's map and then exit from the railing in the bottom left hand corner. All of this could mean a couple of things. You enter the house and see the map of Fright Nights, then the deeper you get into the house the closer you get towards the map of HHN XX. After you pass 20's map, then you head up the ramp into the vortex and then you see the past in detail (old houses, characters, ect.) It could also mean that right as you enter the house, you go into the vortex. Once you exit the vortex and go down the ramp, you're now in a possible warehouse with past props, costumes, maps, ect.) You see 20's map right as you exit the votex, then it goes 19, 18, 17, ect. And as you're passing the maps, you see various props and costumes used in that year. Finally you get to the Fright Night's map, then you beging your descent into the past of HHN in detail (full rooms of past houses and chracters.
Half speculation, half my thought-up creation.