The business model (or revenue model) is simply a system by which the game is going to make money. Remember, a game is ultimately a product that needs to be sold, even the most artistic one—surprisingly enough, even the ones that will be given away for free. As we already mentioned, a game concept is not a one-man job by the game designer. Just like game design, creating a game concept is a collaborative work in which the whole team participates and there might be also requirements coming from outside. This includes the business model, and the team needs to have a clear idea of how it will work.
You might think that this is something about marketing that doesn't really concern you, but the business model will have an impact ...