You can make a version of the game that we would like to give to others. Those who can buy the game - to buy "version of the slave" and he gives it to whom he must obey in the game until the game is not completely buy out
In the game you need to consider the cost of, for example, the slave version is - 70%, to fully redeem the slave has to pay another 50% ... you can also do in the slave version some limitations
