Tit for Tat: the king of Prisoner’s Dilemma strategies. Its simplicity masks its depth…but it can be beaten!
A fantastic interview with Press about his findings - https://www.edge.org/conversation/william_h_press-freeman_dyson-on-iterated-prisoners-dilemma-contains-strategies-that
An overview of the various algorithms pitted against each other in Axelrod and Press/Dyson’s battle royale - http://axelrod.readthedocs.io/en/stable/reference/overview_of_strategies.html
http://www.sfs.uni-tuebingen.de/~roland/Literature/Axelrod(81)_the_evolution_of_cooperation.pdf
A great summary for PNAS of the ZD strategies and their implications - http://www.pnas.org/content/109/26/10409?ijkey=bb6675b0fc7e8e43b584727a2ef974e97efde8efandkeytype2=tf_ipsecsha
A summary of ZD strategy extortion - http://numerical.recipes/whp/StewartPlotkinExtortion2012.pdf
Forbes’s (now dated) piece on the Generous Tit for Tat strategy - https://www.forbes.com/sites/rogerkay/2011/12/19/generous-tit-for-tat-a-winning-strategy/#e9eff3266eb0
A web-based game of the Iterated Prisoner’s Dilemma - http://ncase.me/trust/