I consider this to be a true prisoner’s dilemma already (basically, any prisoner’s dilemma is true if it’s written out in numbers and you believe that the numbers really capture everything). You can make it more paperclippy by substituting fi(Sj) = 0.
To make this more interesting, interpret it as a true prisoner’s dilemma. I.E. the aliens care about something stupid like maximizing paperclips.
I consider this to be a true prisoner’s dilemma already (basically, any prisoner’s dilemma is true if it’s written out in numbers and you believe that the numbers really capture everything). You can make it more paperclippy by substituting fi(Sj) = 0.