Two-player is the "magic number" for co-op, Call of Duty: Modern Warfare developer Infinity Ward has said.

The last Call of Duty game, Treyarch's World at War, featured four-player campaign co-op and a bonus four-player survival Zombie Mode.

Call of Duty: Modern Warfare 2, due out worldwide on November 10, won't have a campaign co-op mode at all. Instead it will have a two-player Special Ops mode, "designed to be replayed over and over again".

Speaking to, Robert Bowling, director of communications/community manager at Infinity Ward, explained the decision, saying it didn't want to "ruin the story by cramming co-op into it".

He said: "We don't do co-op in our story because we're crafting a very specific experience and we don't want to ruin that by cramming co-op into it. We take the moments that work really well with co-op, we bring them out and we put them in Special Ops."

"Story's all about pacing," he added. "Sometimes moments get toned down because they don't fit with the pacing of the experience you're trying to deliver. There (in Special Ops) it's all about fun. It's about playing over and over again, getting a better time - you'll have a time at the end of it - it's about challenging a friend going in on co-op and trying to beat it on veteran."

When asked why Special Ops was limited to two players, not four, Bowling replied: "Two player seemed to be the magic number for co-op. That's when it stayed really fun and intense without becoming a clusterf**k of things. We just found that two-players was the most fun."

To see how Modern Warfare 2's shaping up, check out our first-look preview.

What do you think readers? Is two-player the "magic number" for co-op? Let us know in the comments section below.