Reciprocity is necessary but one of the best strategies for iterated prisoner's dilemma is tit-for-tat or "equivalent retaliation". https://en.wikipedia.org/wik

Reciprocity is necessary but one of the best strategies for iterated prisoner's dilemma is tit-for-tat or "equivalent retaliation". https://en.wikipedia.org/wiki/Tit_for_tat https://en.wikipedia.org/wiki/Tit_for_tat You always start out by cooperating but if someone defects on you, you defect on them.