The closest thing that would be easy for you to use is to obtain the freely available sourcecode and SDKs for most of the major game engines. These are the same tools that game mod makers use to create modifications to these games. You would have to write your our extensions to create the appropriate controls for moving and modifying your characters in realtime, but it could be done pretty easily. ANd the good part is that because it is for broadcast TV, you only have to work with a really low resolution (less than 500x500, so you can do A LOT with no slowdown, even in realtime.