We looked at experiences like Team Fortress 2, in which there are dependencies on classes, and games like World of Warcraft, in which there are large amounts of people working in tandem, creating this kind of epic synergy to overcome these encounters that wouldn't be overcomeable as an individual.
We really wanted to focus on teamwork and the buzz that comes from people working together online, because even though there's some downtime when you're not playing together, the buzz is that much higher when the group locks together and everything falls into place.
These are the words of Jake Biegel, the lead designer of co-op for Resistance 2. (That's a real job? Sign us up!)