Very simple and effective.
Maybe some light background music would be nice.
And maybe win you win, have some cheering. And when you lose have some 'awwwws' or something.
I thought it was funny, that regardless of what happens, when you click the 'x' in the top left, you get a message that says 'you win'. It implies, that you're a winner if you can pull yourself away from the gambling table.