The mobile game markets are increasingly competitive and the game publishers are looking for new ways to increase player retention and cross commercialization of games. In this paper, we examine how a purchasing system using virtual currency based common market can be designed and implemented in order to create a larger service platform. The solution enables cross-game purchasing of virtual items from one game into another. We present how such a system can be designed, how it would fit into larger vision of multi-game ecosystem and what kind of limitations there are when implementing such a system. As a result, we describe solution of a bank and a marketplace entity, which are responsible of the transactions, virtual items and connecting games to each other. As a conclusion, we are presenting the expected challenges and expansion plans for the common market system.