Still more on prisoners’ dilemma

Tit-for-Tat was long considered to be the most effective strategy. However, a team from Southampton University in England introduced a new strategy at the 20th-anniversary Iterated Prisoner's Dilemma competition held in 2004, which proved to be more successful. This strategy relied on cooperation between programs to achieve the highest number of points for a single program. The University submitted 60 programs to the competition, which were designed to recognize each other through a series of five to ten moves at the start. Once this recognition was made, one program would always cooperate and the other would always defect, assuring the maximum number of points for the defector.

If the program realized that it was playing a non-Southampton player, it would continuously defect in an attempt to minimize the score of the competing program.

There is a key point to be remembered - It requires connivance and collusion of a significant proportion of players to beat strategies that have the characteristics of “Tit for Tat” – nice, retaliatory, forgiving and non-envious. This is possible in many cases such as oil cartel, monopolies and cartels in limited geographies, uneven power equation, etc.
However, for most individuals living in society and having a large number of interactions with many people, there needs to be no fear of a large number of them ganging up.