One of my personal favorite things about Call of Duty 4: Modern Warfare was that it was concise.

MB: I think we learned on Call of Duty 2 that we need to be very careful with our pacing because you can kind of ruin moments by numbing people to them.

One of the big differences for me between 2 and 4 is that with 2, there were still a lot of times where I could just kind of screw around and where I actually wound up going the wrong direction in the level and finding the end of the map, and throwing potatoes at people...

MB: That was fun, wasn't it? I don't know if we shipped like this, but there was a point where the potatoes would stick to people.

They didn't usually, but the guy you were supposed to interrogate, you could get them in his lap.

MB: There was a point there where -- I forget the guy's name, but the sergeant major type guy who was training him -- I had potatoes stuck all over him.

In Call of Duty 4: Modern Warfare, I didn't really have time to screw around, and I always felt like the thing that the game wants me to do is compelling enough that I'm going to do it; I'm not going to go try to get out of the map in order to try and "conquer" it.

MB: That's always been our goal. I think that's just a sign of -- I can't take credit for this myself -- the skills of the storytelling and design team just kind of maturing, and the focus of Call of Duty 4: Modern Warfare being a more fast-paced, focused game.

We put a lot of effort in subtle ways to encourage and inspire the player to do what we wanted them to do through design.

Another thing that helps is the believability of the characters, and you can sometimes get into that uncanny valley with COD4.

MB: I think the trick to gradually traversing it is to focus on going as far as you can with the character model itself. Then look at ways to enhance that model with improving elements affecting it. Such as the lighting, self-shadowing techniques, and other ways to improve not just the model itself but how it's viewed naturally in the world.

With Call of Duty 4: Modern Warfare specifically, we're fighting in war-torn environments and the characters are rugged and dirty, so the "put dirt on it" technique works well.

Putting dirt on things and that sort of stuff, it does work, but then people do sort of recognize patterns and things like that. So, how can you kind of get around that? What's your method for non-repeating textures, and things like that?

MB: Well, first of all, I'll say one of the hardest things we did in Call of Duty 4: Modern Warfare was make people stop putting dirt all over everything. We finally had a lighting engine that was good enough that you didn't need to do any of that. And we're still pushing on this, put dirt on the right places, but don't put heavy dirt on everything.

Yeah, that was a huge deal in Call of Duty 4: Modern Warfare. And still, to this day, we get art applicants, and I'm like, "No, they're still doing it the old way. There's dirt on everything all the time." To get around that, good lighting is key.

In terms of repeating textures, we repeat textures quite a lot, actually. But you usually want to change them up, like you have a texture that repeats one and a half times, and no one's going to see it.

And then you change to something else, and then you change back again, and it's fine. You have a texture that has some really obvious repeating elements, and you put a window on top of one of them, and no one notices the texture repeats.