Show HN: I built a jigsaw puzzle website 5 years ago
Great site! Love the idea. I would love to see the ability to alter the background color. I may also suggest you never default the background to pure black.
https://gomakethings.com/design-tip-never-use-black/
You will now notice this on most websites you visit.
You may also consider adding more sound effects and/or royalty free light background music that can be toggled on/off.
Good luck!