If you accept updateless decision-making (caring about alternative possibilities, or equivalently deciding on your strategies in advance), this is equivalent to PD, with payoff depending of your and alien’s strategies, computed as expected utility through the uncertainty of the coin.
If you accept updateless decision-making (caring about alternative possibilities, or equivalently deciding on your strategies in advance), this is equivalent to PD, with payoff depending of your and alien’s strategies, computed as expected utility through the uncertainty of the coin.