There are now a number of games that are providing real tokens as the currency for a game.
Tokens, Coins, Gems, Points or whatever they may call it, tokens has always been linked to success in a game.
Making that token on universal blockchain and off game trading would enable higher amount of in game purchase for freemiums.
A lot of games now use the in-game currency system, but not in all games, in-game currency is also a means of payment in the real world, this could greatly help in the distribution of cryptocurrency.