Bigger game image

Hi, first of all great work done on giantbomb API. I want to fetch larger size image of the game which I want to show in slider on my site. So it should be be bigger in size like 1200*400 or near to that. I have checked all image sizes got from API including screen image, medium image, thumbnail image but all are small images. Not getting how to get larger size image. Please help me out here. Currently I have fetched screen size image but it is streached in my site slider and not looking good. I would be greatful if I get the solution for it. Thanks in advance.