The short answer is that it's all Brazil's fault. In the '80s, some executives for Japan's Fuji TV happened to be in Brazil during Carnival, and they liked what they saw -- and not just the barely covered boobies everywhere, but also the concept of throwing one giant crazy party in the streets. So they decided to organize a 44-day festival of their own, which they called Yume Kojo ("Dream Factory"), because it was supposed to revolve around dreams and imagination. Somehow that translated into "masks everywhere, all the time."
Yume Kojo '87All those Shy Guys you kill are regular people looking to get day drunk.
As part of the year-long media blitz to promote the festival, Fuji TV commissioned Nintendo to make a Yume Kojo video game. Nintendo threw the festival's visual elements (including its turban-wearing mascot, Imaji) into a blender with an existing prototype of theirs, and what came out was Doki Doki Panic.
Even after they ditched Imaji and turned the game into a Mario title for international release, Nintendo still kept Yume Kojo-related elements, like the masks and the dreaming theme. The game ends with the revelation that Mario dreamed the whole thing, after all. Considering how long the real festival went on for, and how hard they tried to push it on people, we can't blame Mario for having a stress nightmare in which he goes around pelting festival-goers with vegetables and throwing them into bottomless pits and such.
Related: 6 Video Games That Came Bundled With Filthy, Filthy Lies
The Wolfenstein Reboot Series Owes A Debt To ... Yahtzee?
The only plot in the original Wolfenstein games was "Hey, there are Nazis here. Kill them." When the series was rebooted this decade, one of the main innovations was adding an elaborate story, complex characters, and actual emotion to the ol' formula. How did they do that? Easy! By taking notes from Zero Punctuation. Yes, the jokey game review series by extremely British critic Ben "Yahtzee" Croshaw. Specifically, the joke video about Duke Nukem Forever.