the big difference in that room pictured and mine is that mine is the opposite - the flat walls are on the sides on the house, not the front and back. the front and back of the house have the angled ceilings (and windows), with little walk ways into where the windows are.
the idea is black out both windows and install a curtain of some sort over one of the walk ways, and build the other one into a media rack (and frige!) that will have a small pc and an xbox connected to a receiver and then onto a projector. ive been hoping to find a receiver that can do picture in picture with two separate video sources. that way i could have to two tv programs (march madness, nhl and nfl) on at once (one from the pc, one from the 360).
the walls will just be painted a dark color with a very non shiny paint, probably black. before i paint them im going to lay down speaker wire in the ceiling for 11 channels, just so i wont have to rip the plaster apart when i want to go up from 7 to 9 to 11.
im still waiting for projector prices to drop to do anything. you can get a 1080p 3D projector now for around $1500, but it is active shutter, meaning that I need a $100 pair of battery powered glasses for each viewer.
what i'd like to do is use two normal projectors connected to an Optoma 3DXL video processor that will take a 3D video and send each eye to it's own projector. the problem is that you need a projector with a shiftable lense to converge the two images. when those come down into the $1000 range I'll make my move. the other problem is the relatively short distance across the room means ill need a projector with a shorter throw distance.
the other major factor that is causing this to cost more than i want is furniture - the hallway leading to the 3rd floor is so narrow the furniture has to be extremely modular to fit and most of that stuff (think lovesac) is way more money.
something like this would be optimal but would never fit (and would cost way too much)
ive also honestly considered a patio sectional, since it would be a bit easier to get moved in. if i wanted to do it all now and use a basic 2D projector I have it figured at $3,000 to buy paint, a projector, receiver, very basic pc, and materials to build the screen.