DALLAS (CNN/Money) – Typically, when a developer sells roughly 300,000 copies of its game in one week, the team takes a little downtime to unwind and celebrate. At id Software, downtime is a rare commodity.

Just 10 days after the release of "Doom 3," the developer is already at work on its next title. It's early, of course, and CEO Todd Hollenshead said he doesn't expect any of the work currently being done will find its way into the final product, but ideas are already being explored.

When work started on "Doom 3" four years ago, the entire gaming world knew about it, due to internal strife at id. This time, the small team is on the same page and playing things closer to the vest. The next game's plot, title, theme – even its genre – are company secrets. And Hollenshead gives only the vaguest of hints.

"Our roots are in the horror/action genre," he said over lunch at QuakeCon, the ongoing annual fan event for fans of id's games. "That suits our tastes and talents. We're thinking about something up that alley. ... [That said], we're keeping the idea vault open. 'Quake' and 'Doom' were both basically a sci-fi game. 'Wolfenstein' was a World War II game. I'd like to try something new."

From a technical standpoint, id's next game will not be as revolutionary as "Doom 3," said Hollenshead. The focus this time is to do something that's remarkably difficult in the gaming world: Establish a new franchise.

"Starting from scratch is always tough," he said. "I believe that id as a studio, because of what [technical director] John [Carmack] can do with technology and because of how we speak to our fan base, is in the perfect position to build an IP [intellectual property]."

In keeping with id's PC-centric history, the company's current plan is to build a PC focused title, said Hollenshead, although it is studying next generation consoles as well.

In its first week on store shelves, "Doom 3" sold roughly 300,000 copies.

Of course, before that new game makes its way onto store shelves, id has a lot of other projects on its plate. Friday, it will launch "Doom 3" in Europe, which could double the existing sales numbers within a week. And a demo of the game for skeptical gamers who demand hands-on time before spending $55 is "imminent". At the latest, said Hollenshead, it should be released next week, with two or three hours worth of gameplay.

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The company is also working to secure a deal for a follow up to 2001's "Return to Castle Wolfenstein." In a recent television interview, Hollenshead inadvertently announced the sequel, but because of delays in signing a third party developer (id will not be making the game itself, but overseeing development of it) he is now a bit gunshy on the topic.

"It goes without saying that there will be a 'Return to Castle Wolfenstein 2' in the future," he said. "I mean, the first game sold over a million copies. The sequel is a matter of time and logistics."

Will it use "Doom 3"'s revolutionary graphics engine?

"That would be my expectation."

Expansion packs to "Doom 3" are likely as well. Again, id would not do these directly, but would oversee their development.

"That's something we want to do," said Hollenshead, "but we have to just get to the point where we say 'yeah, we're doing it.'"

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With the game engine finalized (though Carmack continues to add new features based on future video technology), licensing can begin. Raven Software has licensed the engine for the still-under-wraps "Quake 4". And an as-yet unidentified developer will use it for a forthcoming game.

"It will be a name that people recognize," is all Hollenshead will say.

Lest console gamers feel unloved, work continues on the Xbox version of "Doom 3". Though publisher Activision (ATVI: Research, Estimates) is pushing id and Vicarious Visions (the developer working on the console version) for a 2004 release, user interface issues and the limitations of the Xbox's technology might make that impossible.

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"It's still up in the air," said Hollenshead. "It could happen, but that's not our focus right now. Our focus is on the gameplay. ... 'Doom 3' is a game that on the PC is very finely tuned. There was a lot of play balancing. The stuff that was supposed to be tense resulted in a lot of tension for players. The stuff that was supposed to be scary makes people crap their pants. We want the Xbox version to be just as good."

Finally, there's the long-in-development "Doom" movie. Bounced around Hollywood for years, the rights to the film now rest with Universal Pictures. And, barring production delays, it now looks like the film could be a reality.

Shooting is set to begin this fall in Prague, said Hollenshead. A script is in hand. And pre-production is already underway.

"I have never been more confident that there will be a Doom movie in the next 18 months," he said.  

Morris is Director of Content Development for CNN/Money. Click here to send him an email.