The games run through script, look how this guy create a game in casino https://www.youtube.com/watch?v=l5bRPWxun4A

If you really able to create a game and it successfully created, it's already easy since you only need to contact the casino through email. If your game is really interesting/exciting, they will want it.

Then it's up to you whether you want to sell the script or just want to rent your game.