The history of video games is the story of ripoffs, knock-offs and sequels that surpass their sources, and that’s particularly true of this 1981 classic. An initially unauthorized variation on the original Pac-Man, it fixed the flaws of its model (by making the ghosts’ movement more unpredictable so that it required strategy rather than muscle memory to play, making the maze easier to see, and throwing in some visual variety to break up the singleminded monotony of the dots-and-monsters chase), and otherwise didn’t mess with the compulsively playable formula. And it’s arguably the most popular arcade game ever to feature a female protagonist.