I think Magic Carpet is one exercise you can use, Its fun, effective and really enjoyable game.
you just need a small carpet, if 4 people can stand on carpet freely then add another one or two so that they have very little space and as this is timed game this will make the task more difficult.
Now tell them the carpet fly's once they turn it upside down and in process of turning the carpet no one must step out of the carpet and must turn the carpet in 1 minute.
Try this out its timed, team work game. I have tried this in my sessions and got my point across as soon as i finished my game.
Your task would be to keep an eye on people who steps out. if any one, even puts his/her toe out ask the whole team to stop the game.
Start your session with what they have done and what they could have done.
Let me know what you think of it and if you use this game in your session let me know how it worked
If you debrief effectively, it should bring out all aspects of team working..
learning has to come as realization not instructional and therefor will be subtle unless participant are children..
In this case some cues may be how did they feel?
what were they worried?
Are worries common?
Were they thinking about not being individual defaulter causing loss to the team?
what was there in their mind all through.
was there cooperation amongst people? level of cooperation?
did any one feel uncomfortable ( personal space) etc.
Play based on the response you get from the group.
I also agree you may find may other games ( better) which are not common and drive this message much more effectively.
Brief them that they can be outrageous - why not have a party at an exclusive restaurant, or launch a hypothetical new web site and invite some guesst. After all, it's hypothetical and I think you will find that in the in the excitement of a party, the "team" can plan anything, but when it comes time to take on a single responsibility, they'll slow down.
Then bunch them together again to help each other with their tasks, and they have become an organised group!