Find organizations that are already sponsoring or buying gamification for their online marketing, and approach them.

If you make gaming apps, look at who is already promoting their products or services through similar means.

You have a common issue here which is this: for most prospects, you'll have to make TWO sales. I dislike this situation and avoid it whenever I can. First, you must sell them on the *idea* of your solution ("This game will help you increase customer involvement and retention, and convert into more sales".) Second, you must sell them on the idea of *you* as the solution provider.

I look for situations where there is only the one sale to be made: you as the solution provider. If you have to sell them on the original idea, it's too much work.

If they're already using these media to reach their target market, they already know its value. You don't have to sell them on that. You just have to get their attention and assure them that you will get them results.