'with communication' does a lot of work here. tit for tat is a strategy where you start with the positive-for-both-parties strategy and then just copy whatever the other party did last time.

Yes but the only way repeated cooperation can be maintained is if players can “punish” defectors by also defecting for a certain # of turns (thus making the PV of breaking ranks and defecting < keeping cooperating for every player).

SBF’s situation is different in that the game ends as soon as someone defects.