Sounds like a development question. Certainly the eDGe can "link" to other Bluetooth devices, and since it uses headsets, it can send and receive. If the actual comm control is not exposed through the API, it may only do audio for some reason. The game would have to be written to support comm by Bluetooth rather than LAN.

Or you could make your phone act as a wireless access point, and as such, a gateway or SWITCH, which would allow two eDGes to talk across the LAN, but even then the game would have to accommodate it.
Most games designed for multi-player use an internet-based server, with an account on that server. That way, people all over the world can play against one another, but more importantly, it can generate RECURRING REVENUE!!! (the two most important words in business school doncha know!)