Here's the idea - you would love to make a movie in which you, or an actor of your choice, appears in a computer game. Its not actually a new idea. It is an example of "Machinima" which has been around since the 1980s. Here's what Wikipedia defines it as:
"Machinima is the use of real-time computer graphics engines to create a cinematic production. Most often video games are used to generate the computer animation."
Its quite a flexible term. For example here the X-Plane flight simulator with two actors, filmed at Finchley Film Makers in one evening session (3 hours to include everything from setting up the green screen and welcoming the actors, to packing up!):