Direct reciprocity, typically studied using the Iterated Prisoner's Dilemma (IPD), is central to understanding how cooperation evolves. In the 1980s, Robert Axelrod organized two influential IPD computer tournaments, where Tit for Tat (TFT) emerged as the winner. Yet the archival record is incomplete: for the first tournament only a report survives, and for the second the submitted Fortran strategies remain but not the final tournament code. This gap raises questions about the reproducibility of these historically influential results. We recreate the second tournament by restoring the surviving Fortran implementations to compile with modern compilers and by building a Python interface that calls the original strategy functions without modification. Using the open-source Axelrod-Python library to run tournaments, we reproduce Axelrod's main findings: TFT prevails, and successful play tends to be cooperative, responsive to defection, and willing to forgive. Strategy rankings remain mostly unchanged. We then assess the robustness of the originally submitted strategies by incorporating additional strategies, and we run one of the largest IPD tournaments to date. We find that the original tournament was especially favorable to TFT and that it is difficult to dethrone TFT when the original submissions make up the majority of the field. We also observe that several lesser-known submissions perform strongly in more diverse settings and under noise. Our contributions are: (i) the first systematic reproduction of Axelrod's second tournament; (ii) a contemporary reassessment of the original results in light of new strategies and settings; and (iii) a preserved, easy-to-use implementation of the second-tournament strategies within Axelrod-Python to support future research.

翻译：直接互惠通常通过迭代囚徒困境进行研究，是理解合作如何演化的核心。20世纪80年代，罗伯特·阿克塞尔罗德组织了两场具有影响力的迭代囚徒困境计算机锦标赛，其中"以牙还牙"策略脱颖而出成为赢家。然而档案记录并不完整：第一届锦标赛仅存一份报告，第二届锦标赛虽保留了提交的Fortran策略代码，但最终比赛代码已遗失。这一空白引发了关于这些具有历史影响力的结果可复现性的疑问。我们通过恢复遗留的Fortran实现使其能在现代编译器下编译，并构建了直接调用原始策略函数（未经修改）的Python接口，成功重建了第二届锦标赛。使用开源的Axelrod-Python库运行比赛后，我们复现了阿克塞尔罗德的主要发现：以牙还牙策略胜出，成功的策略往往具有合作性、对背叛行为作出反应且愿意宽恕的特点。策略排名基本保持不变。随后，我们通过引入额外策略评估了原始提交策略的鲁棒性，并运行了迄今为止规模最大的迭代囚徒困境锦标赛之一。我们发现原始锦标赛对以牙还牙策略特别有利，当原始提交策略构成参赛主体时，很难撼动以牙还牙的统治地位。我们还观察到若干知名度较低的提交策略在更多样化的环境和噪声条件下表现强劲。我们的贡献包括：（1）首次系统复现阿克塞尔罗德第二届锦标赛；（2）结合新策略和新环境对原始结果进行当代重评估；（3）在Axelrod-Python中保存了易于使用的第二届锦标赛策略实现，以支持未来研究。