I had the same issue with obscure games a while back. When I couldn't find any box art or backgrounds for these small freeware games, I started making my own. It felt a bit silly at first, but it turned out to be a fun project. To add some randomness, I used to Roll a D10 to decide on various elements and backgrounds. It was a bit of a trial-and-error process, but it really helped bring those games to life and make them feel more personalized.