I read an article a while back where Carmack was talking about possibly concentrating on a 3D engine that was basically a full studio. You could create a game, or a 3D full length movie in it if you wanted to. He said that he wasn't far off from doing "Toy Story" type graphics in realtime 3D anyway. I thought this sounded pretty cool.
He comes up with new ideas all the time though, then he just ends up working on the next "quake" or something.. so who knows.
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He cut the possum's face off then cut around the eye socket. In the center of the belt buckle, where the possum's eye would be, he has placed a small piece of wood from his old '52 Ford's home made railroad tie bumper. Damn, he misses that truck.