Try unzipping the folder and then playing it. The images should work that way. It didn't occur to me until a few minutes ago that it was even possible to launch the game from inside the zip folder, but then I went and tried it, and sure enough the images didn't work that way. I'm a relic of an older time when the contents of zip folders were impossible to access without unzipping first; using files that are still zipped is completely outside my mental box, you know?