How's this for meta: A recently created mod allows gamers to play the original Doom within Doom 3.
Did I blow your mind apart yet?
Terminal DOOM is a demonstration of the possiblities of interactive surfaces within Doom 3.
I can't wait to play Doom in a terminal in Doom 3 while I'm playing Doom 3 within Doom 5 and waiting for Doom 7 to download from my personal satellite.
Thinking about that just gave me a stroke.
battleteam.net: Proof Of Concept: Terminal DOOM