That would be cool, here is a fair way to do that.
Charge between $40 to $60 dollars for it depending on the content input and make it a stand alone game. At the same time give the option of anyone that already bought the multi player portion to pick it up for $10 to $20.
Some people won't care for it some will want both and some will only want the single player.
Edit: I don't see why the hatefull 60 bucks for half a game comments are being made. The game was built as a multi player game, and currently thats what it is. I actually have the game unlike just about anyone who conplains and I can tell you it's worth every penny.
check me in a month's time to see if I still feel that way...








