GameStop CEO Ryan Cohen is trying to buy the popular auction site eBay for $56 billion. He’s now laid out a new angle of his vision, and it involves video games. In a recent interview, Cohen said one previously unannounced part of his plan to help eBay return to growth–if he can successfully take it over-is by creating a marketplace for digital gaming items. eBay has already flatly rejected Cohen’s proposal to buy the company, saying it was “neither credible…