Could it be that this game you've created will have to be your "baby" for a few years before you can pitch it anywhere? If it's something you really want to do, cherish and nuture the idea, but also do other things - these can provide new perspectives on your game and help you revise it. You mentioned writing for television, so this must give you some idea of how it works. It might be you have to develop a relationship with a games developer first.
My suggestion would be keep the idea in your head and focus on getting a foot in the door writing other things such as television and other games. They may not be as interesting to you, but showing games developers what you can do is essential. Once you have something established with a developer, mention the idea in passing, and see what they say. It can only grow from there.
I know I don't have much experience in this area, but I hope this helps