can't believe no one's pointed out that the best strategy to win the most money is ALWAYS to cooperate and split the money equally every time... the tokens and the briefcase at the end are there to distract. if they'd followed a 100% cooperation strategy each of them would have had $2000 at the end. not even the people who cheated in this ended up with more money than if they'd cooperated fully from the start. (obviously assuming the person who wins the briefcase at the end doesn't do a runner... but hopefully you've built enough trust by then to know they won't.)