DarklinkUK on Reddit has put together quite the collection of Wallpapers. 52,000 of them to be precise. Not all of them are video game focused, but man... if you're searching for a new wallpaper you could do a lot worse.
I'm going to warn you though. This is a time sink. A massive timesink. If you're anything like me you are about to transport yourself into a world of pain, sifting through thousands of wallpapers... image after image. Look for the perfect wallpaper.
I'm so sorry. I'm sorry I've done this to you. Please accept my sincerest apologies.