I have quite a bit of experience with this. My advice is to create a plug in tool that can be licensed not just in the entertainment vertical but other similar verticals. That's one key way to develop clients that will never leave you because it will be part of their business.
Then as a business you can focus on product enhancements and cross promotions to new verticals.
Gameify-ing is the way to go and the entertainment industry will love you for it, so that means get ready for copycats. It should be a plug in to whatever site you are finding that your audience is stuck on. For example, many don't want to leave Facebook. Make it an app for that format. Hope this helps.