My first thought was
But once I got over that, the best way I find, is to say (Like most people here it seems
) that your wife or girlfriend bought the game for you, but you either don't want it, doesn't meet your system requirements etc or something like that.
Very, very rarely will somewhere not let you return a gift item, at least for store credit.
But it depends on your company's policy on returns, I've had games from the olden days that had a bug that flat out wouldn't run without a patch (This was before I had the internet) due to a runtime conflict, and wasn't allowed to return it, basically unless the disc is cracked or not working on their test PC.