I'm making a game right now and thinking about the possibility of providing way for users to produce and share their own levels for the game. To help incentivize people to do that, I figure I could operate an in-app marketplace where users can buy and sell their custom levels. Would that be permissible in a game distributed on the iOS and Mac App Stores, or is there some rule that I'd be violating by having such a feature in my game? If this is permissible, how would you recommend I do this? One possibility I considered: I could have users buy virtual currency via IAP and then transfer that currency to whoever created the level upon the purchase of a custom level. The creator could then spend their virtual currency on other custom levels, or they could provide me with, IE, their PayPal information and I could pay them through that. Or I could mail them a check. Or could I somehow send it via direct deposit like Apple does for app developers? Obviously I'd be taking a cut of the money so I'm okay if whatever I end up doing has a small fee associated with it. I'm just looking for other suggestions of how to do this.