Changing from the standard expected fare of most FPS games that focus on the individual, to a game that requires teamwork took me a day and a certain amount of grumbling.
Then I took a step back, to the days when as a member of a gaming clan I worked with my team mates to accomplish an objective. Good times, fierce battles and friendships which have persisted for over a decade were the result of this team work, as well as the sense of having my friends back me up and backing them up in return.
Team fortress, Q3F, Wolfenstein: Enemy Territory, Enemy Territory: Quake Wars and in more modern times L4D and L4D2 are all games which require teamwork, yet Brink takes this one step further.