If possible I would Imagine a wizard that would guide a single player game transitions to a multiplayer game.I would work as the facebook intergration or phonegap export in c2.
I know its a dream but would be very very cool for game builders.
Meant that the option should be part of C2 and not in other 3rd party SDKs
Develop games in your browser. Powerful, performant & highly capable.
An inbuilt multiplayer system will be better.