Before revision:  A class of successful strategies of direct reciprocity were recently found for the iterated prisoner's dilemma Yi et al., J. Theor. Biol. (2017) and for the three-person iterated public goods game Murase and Baek, J. Theor.
After revision:  A class of successful strategies of direct reciprocity were recently found for the iterated prisoner's dilemma and for the three-person iterated public goods game Murase and Baek, J. Theor.