Today John Carmack revealed at QuakeCon ’08 that the “next Doom” — which we’ll call Doom 4, for now — is in development and looking good.
“The next DOOM game will look like it’s built on another engine, as it uses three times the horsepower.” It’ll operate at 30 frames per second. — 1UP, quoting Carmack
He also said that Doom 4’s multiplayer will be “more extensive” than Doom 3’s.
The more advanced graphics do come at a cost, though. In comparison, RAGE runs at 60 frames per second.