In the course of a technical talk at last weekend's QuakeCon convention, id Software programmer John Carmack divulged a number of details about the company's forthcoming Doom game. The game will have multiplayer support, but will definitely emphasize the single-player mode, according to 3D Action Planet's report on the talk. Responding to earlier comments by id's designer Graeme Devine that the company had been developing a party-based online action game called Quest, Carmack stated in a Slashdot.org posting that he would have work on an "extensible virtual world," while most of id wanted "to work on a game with a story."
As many at the talk have noted, id will not be using the Quake III: Arena engine for the upcoming Doom game, but will instead program the entire game from scratch. The new Doom game will also feature a built-in game editor - one that will be much easier to learn and use than Quake III's existing tools. Said Carmack, "I do think there are real benefits to the user community in having the tools with the game."
Doom will be primarily developed for the PC, though Linux and MacOS versions are also in development. Doom will also likely be ported to Microsoft's Xbox console, though probably several months behind the PC release. Carmack's remarks indicate that it's less likely that the game will appear on the Dreamcast or Playstation 2 consoles.