(Image credit: Bungie) Weird Weekend Weird Weekend is our regular Saturday feature where we celebrate PC gaming oddities: peculiar games, strange bits of trivia, forgotten history. Pop back every weekend to find out what Jeremy, Josh and Rick have become obsessed with this time, whether it's the canon height of Thief's Garrett or that time someone in the Vatican pirated Football Manager . In the shadows of the bio-research lab in Dire Marsh, there's a strange strip of graffiti, scrawled behind a rack of hazmat suits in luminescent pink. It would be just another disturbing example of Tau Ceti IV's decline, as its colonists succumbed to disease and infighting—easy to miss among the planet's many horrors. Were it not for the fact that it also features in Marathon 's promo art. You've likely seen this graffiti plastered across the game's Steam page, or other articles on PC Gamer. And over the last month, I've come to understand its meaning.…