From Cryptonic Technologies:
SimpleYahtzee is a Yahtzee game for your Mac. Basic idea of the game is that you have five six-sided dice to roll three times to achieve the best value possible on each turn. There are 13 different scoring boxes and the game does not end until all 13 are filled. Different boxes require different combinations of dice (see the section on Scoring the Game below) to get good scores. Each turn consists of 3 rolls of the dice. At the start of each turn, the user rolls all the dice. Prior to each subsequent roll the player may choose to hold or release any combination of dice. After the third roll, the player must score the set of dice in one of the scoring boxes.