A new wave of epic games seeks to liberate players from predetermined plots. Robert Colvile reports
It's one of the most dramatic scenes in the Star Wars trilogy: Darth Vader, newly revealed as Luke Skywalker's father, makes the kid an offer he can't refuse: "Join me, and we can rule the galaxy as father and son." Luke, being the goody-two-shoes that he is, says no, gets his hand cut off, and plummets to his near-death. But what if he'd said yes?