brain teasers This addictive Morse code game is the new Wordle you never knew you needed Ellsworth Toohey
puzzles This multiple choice probability puzzle has been causing arguments for years Mark Frauenfelder
useful stuff Excellent cheap puzzle book: The Moscow Puzzles: 359 Mathematical Recreations Mark Frauenfelder
puzzles Can we wrap a 1x1x1 cube with the blue 3×3 piece of paper, cutting along some edges without disconnecting it? Mark Frauenfelder