I'm writing this topic to discuss a free game named GoldenTowns where is possible sell the money produced for bitcoins or fiat.

Currently 1 gold it's negotiate by 4.3/4.75 euros or the equivalent on bitcoins.

You can focus in building the city, militar simulation, politics or even in exchange (buy and sell) of the many resources by means of price arbitration of prices. 

The interesting is that the money of the game is actually covered by a growing amount of real gold, which means, all the economy of the game is based in a deflationary currency.

This game is based on a paper which describes a deflationary economic system. 

Kisses and sorry for my bad english =)