UK web developer for 10+ years, I'm also a professional web designer. Experience building multiple javasscript sites and applications for Pearson UK, UK universities and councils.
This project would require a written set of requirements to be signed off with client.
From your initial description, it would mostly require HTML5, JavaScript/Jquery code to produce a simple game. Using HTML5 this can be made into a responsive (scalable multi device) game. The requirements will need to be sent through and signed off by both sides considering the budget in terms of complexity.
HTML5 and Jquery on its own can add many great features to website/game interaction such as animation.
I look forward to hearing from you to start the work.
Thanks,
Dan