I am thinking that in game like x3 or gta instead of having "credits" you have to really transfer coin to buy the stuff in the game and you
get money for making missions to your wallet but that wont make the testnet bitcoin having any value.

And i am thinking that it be integrated to android games because everyone has a mobile phone
but it would work for other platform to. In the games there are
buyers and sellers for stuff that you need to go forward in the game.
Think like the pc game capitalism or the facebook game "farming" or what its name was.

Maybe make a game like Entropia universe.