aftergame

A second game played to reverse the outcome of the first; the means employed after the first turn of affairs.

1597, Michael Drayton, Englands Heroicall Epistles, London: N. Ling, 1603, “Charles Brandon Duke of Suffolk, to Mary the French Queene,” Twere ouer-sight in that at which we ayme, / To put the hazard on an after-game;

so many thousand faithfull and valiant English men, who left us in this libertie, bought with thir lives; losing by a strange after game of folly, all the battels we have wonn,

Bonus features, dialogue, etc. accessed when a previously-beaten video game is revisited.