From your words it seems like you've something crazy idea on your sleeves. If you're a developer you should've a portfolio why not approach with this by contacting casino owner's. There's tons of casino.  As a builder perspective you won't know for sure that your game will sustain the market and will be acceptable unless your tried it yourself.

Start with a test project. If you're getting enough response and feedback from user's you can sell your game's exclusive rights to casino sites. It's not like by introducing you someone you could have make this in reality just one day.