Dirty Dice is a Dice-Within-A-Dice game for gambler lovers! There are 4 types of ways to play Dirty Dice: Blanket Craps Twenty-One Dirty Casino Craps Upsmanship "Twenty-One" - Players takes turn with both dice. Each player gets one roll per turn and every roll produces a score. 2 "outer dice" totals count as "plus" score. 2 "inner dice" totals as "minus" score. So the "inner dice" must substract from the total of "outer dice". The object of the game is to accumulate a score of "21" first. Either +21 or -21. For Craps variants look at the game Craps