One important point: You look at a game like Gears of War, where basically the entire game is structured around co-op play--the story, the characters, even how the levels are organized are designed around co-op play. But we have a concept in our game where we have a single ninja whoÂ’s out on a journey of revenge.

What I don't want to do is spoil the key concept and story of the game by artificially tacking on co-op elements. So I won't be doing it for this game, but it's certainly something I've put a lot of thought into.