Cows & Bulls Mastermind is a logic game for guessing a combination of items (colors, numbers or signs). The computer will generate a random combination of four items out of ten available. Each item can be present only once. To play, you select four items and press the Guess button. If an item matches in the correct position, the computer will give you a bull, and if an item matches but not in the correct position, the computer will give you a cow.