"IGNPC: At the Game Developer Conference (GDC) keynote speech back in March, Carmack mentioned that, with each additional game you've worked on, it took longer and longer to develop, and the impression I got was that he was becoming more and more frustrated and that this new rendering technology he's working on for the next game might be his last.

Todd Hollenshead: Well, that would really be a question for John, but he hasn't said anything like that, to me, anyway. He's actually working on new stuff for the Doom 3 technology. Literally, as late as about six weeks before it went gold was when he added in some substantial new features, such as the heat shimmer effect and is already making changes to the engine for what we're going to work on next. I don't know if he's going to rewrite the renderer or not but, ultimately, I think that he's excited about he can do in the future with the renderers. Doom 3 did take a long time, but we certainly don't think that our next game is going to take four-plus years to develop. That's not the plan starting off.

There are a few reasons why it did take so long for Doom 3 to be done, one of which is that the media requirements for a game as big Doom 3 were just very large, and we needed to have a bigger team, and we did ultimately end up with a bigger team finishing the game than when we started on it. The second thing is that¿the term is over-used, but when John architected the rendering technology, it really was a different paradigm in 3D FPS rendering. Whenever you have something that's brand-new like that, there's a learning curve, and the learning curve in this case is compounded by the fact that we didn't have mature tool sets to work with starting off, and also compounded by the fact that it was so dramatically different from the way that we did stuff--even changes from Quake to Quake II to Quake III were obviously significant, but not nearly so significant as the change from Quake III to Doom 3. It was easily at least as big of a difference to go from, say, Doom II to Quake."