Hello Dean
Please check
www.adultgamestemple.com , they're the most versatile adult games you'll ever find on the internet.
You can change practically everything: the pics, the interface, the sounds, the help text the rules...(all external files, jpg mp3 and texts)
Also they have a top10 feature populated only with your members, so it'd be very easy to start contests and give away prizes such as free memberships, t-shirts, caps.... your member retention will increase for sure.
Another important thing: pay once and they're yours for life, without the hassle of a monthly fee.