Dice Games
Dice. That's all you need to put this idea into practice. Create a list where you assign a specific action to each possible roll. For example, assuming a single 6-sided die:
1: Passionate kiss 2: Massage wherever you want for 2 minutes ... 5: such and such position for 1 minute 6: 1 minute of whatever you ask for
The rules of the game are quite simple. It's about rolling the die and performing the action assigned to the roll obtained. A possible variation is to make two lists, each with the favorite practices of each member of the couple, so that the die is rolled in turns and actions from the list of whoever rolled the die are performed. Another twist to the game is to make several lists, as many as possible rolls of the die (for example: one only with massages, another with positions...). In this case, you would have to roll the die twice: the first to choose the list and the second to choose the action within the list.
For more variety of results, several dice can be used. Keep in mind, though, that some combinations are more likely to come up than others (for example, assuming two 6-sided dice, there's only one possible combination for 12 while there are two that lead to 7), so it's advisable to reserve the best rewards for the most unlikely rolls. If you don't want to complicate things by thinking about combinations, you can always use a special 10 or 100-sided die (you can find one in any role-playing game store).
Another alternative, a bit more expensive and less flexible in terms of possibilities, is to get specific dice for this type of game. They can be found in many stores, especially in sex shops, so it won't be hard to get one.