Creating Data Projector Games

[shodai]

I would like to create some simple games that are displayed on a data projector and then use a camera to interact with the game. I have seen this at science centres and the like, but I cannot find any way to do this myself. If you have not seen this before, think of the playing surface being projected on the floor and you can kick the "puck" around the area to play virtual air hockey. There are some software packages that you can buy, but I would rather work from scratch.
Does anyone know of any way to do this? Are there any python extensions/packages that could work for this? If not python does anyone have any other suggestions?
Any guidance or suggestions would be greatly appreciated.