There aren't a lot of details yet but id Software has
announced that they are working on
Doom 4. I'm guessing the game will be using some version of the engine that's powering
Rage and that we'll be shooting demons, imps, and undead marines once again. Hopefully id learned some things from
Doom 3 and we'll actually get decent plot development, weapons with flashlights on them, and fewer monster closets.