Essentially what we were doing is we were taking the Doom 3 engine, which is a linear, first-person, single-player, indoor shooter and creating an outdoor-terrain-rendering multiplayer game with vehicle physics. As a team we were very familiar with id technology but what we really needed to do was something completely new.

Ken and I have talked about this quite a lot. I think if we wanted to we could have put the game out in 2006 and had every map be quite similar. But the problem was it wouldn't have given you that unique gameplay experience at the level of the objective, not just the map itself, but every objective feeling like it's a really different, interesting take on the way that you play. And that was something that we really wanted to achieve.