You will find it here in Live Wallpaper 3D. All you have to do is to open the app, tap on the 3 bars from the top left corner, and find the categories. Select Games and browse the list of contents until you find the preferred one you are looking for. Pictures from your favorite games will be listed here. Tap on the image, see a preview if you like. Following that, simply download it, and set it as your iPhone’s wallpaper.