Thomas Snyder (aka Dr. Sudoku) is a two-time World Sudoku Champion and five-time US Puzzle Champion, as well as the author of several books of puzzles. His puzzles are hand-crafted, with artistic themes, serving as a kind of “cure for the common sudoku.” Each week he posts a new puzzle on his blog, The Art of Puzzles. This week’s prescription is a themed Calcu-doku puzzle for 12/24, with only those numbers as clues.
Via Dr. Sudoku Prescribes: A 12/24 Calcu-doku | Magazine | Wired.com.