Hi there,
Welcome to the boards.
You have a nice looking site there, very clean and simple to use but there just isnt enough content there that will interest people enough to stay and possibly return.
Give them more options, casino reviews, special offers, deal of the month that kind of thing. Start up a newsletter (if you dont already have one) and collect your users details, this way you can market directly to them once or twice a month with some specials that you have.
I think here it is just a case of build on what you have and keep pluging away. Work towards your target keywords and dont get lost trying to offer too much too soon.
Hope it helps.