Scott Phillips of Volition is a man after my own heart. It's enough to know that he had a hand in the bot-tastic Red Faction II, a prime example of how to play competitive games with a co-op twist.
A new blog post from Scott at Edge Online describes a little bit of how Volition approached the co-op aspect of Saints Row 2.
[M]aking the decision to put a lot of effort into co-op, and implementing are two different things. We threw some high level programmers at the project and they got started building the core tech. At the same time we had to figure out how the design was going to work. We had to ask ourselves, ‘what does co-op really mean?’
Is it about having just another person in your world? Is it changing how the game plays, how the AI works and how cars work? It really led to us looking at the fundamentals.
These are good questions; every developer should brainstorm this way! Find Scott's answers in the full article by using the "Source" link below, or by clicking here.