Then I got this comment on my last post:
That links to the following Penny Arcade comic (click for original):
Jesus fucking christ.
It's the same comic. Basically. And don't say "OOOH well one is google maps and one is yahoo maps" because I will punch you in the face. It's the same comic. Map-making website gives bizarre, mysterious RPG like instructions. The end. That's a damn specific joke.
Obviously Randall Munroe reads PA because he's parodied it before. Twice. I think I can say with a pretty high level of confidence that Randall read this comic. I don't care how long ago, he read it, and he copied it almost identically.
He probably forgot about the original, I'm guessing at most he felt the idea was vaguely familiar and decided he was just being crazy and it was all his. Maybe he entirely forgot about PA's comic. He should still acknowledge the similarities and take his comic down.
I'm serious - copying ideas is a big problem in comedy (I'm looking at you, Mencia! asshole!) and I am willing to accept that Munroe just made a mistake, but it's a bad one, and he needs to correct it.
(as an aside, I am currently a few years into the PA archives, and enjoying it a lot, as someone who is not at all a gamer)