In Dec. 1913, an Englishman named Arthur Wynne was tasked with coming up with a new puzzle to run in the New York World. Drawing on a game he remembered called "Magic Squares," Wynne invented a primitive form of the crossword, called "The Word Cross Puzzle," which the World published on December 21. Later editions would set the puzzle in a square grid, add those famous black squares and flip the words in the the name – but Wynne is still considered the father of the modern crossword.
To commemorate the centennial of America's second-favorite Sunday morning activity, Google engineers came up with a crossword-themed version of their iconic Doodle, which doubles as a working puzzle. Google's crossword was created by Merl Reagle, one of the industry's most wildly inventive constructors. (You may even remember him from The Simpsons.)
A word of advice: Don't try to do it in pen.