Is game making "Work Related"

I am a salaried programmer at large corp. with a standard professional contract that states that all my work related creations and inventions belong to the company. I was wondering what kind of step I need to take if I want to make a computer game and claim it as my own. Common sense tells me that a computer game is far from work related but I know that doesn't necessarily translate into the legal world. Does anyone have any advice or resources?

Thanks,
Philip