The product problem
A 404 is necessary but usually forgettable. Once the visitor understands the page is missing, most error screens have no second useful action beyond navigation.
Why this placement can work
A compact puzzle can soften the failure moment without changing what the page means. It is especially useful for products with personality, community or repeat visitors — as long as recovery links remain primary.
Implementation notes
- Keep the HTTP response status as 404.
- Put Home, Search or Back actions before the puzzle.
- Lazy-load the embed after the error explanation.
- Use a source label such as 404-puzzle so the placement can be measured separately.
What to avoid
- Never redirect every missing URL to the puzzle.
- Do not hide the fact that the requested page does not exist.
A practical example
A documentation site shows “We couldn’t find that page”, offers Search and Docs Home, then places a compact “While you’re here” daily puzzle below those recovery actions.
Minimal HTML
<iframe
src="https://puzru.com/embed/?mode=daily&source=404-puzzle&theme=auto&surface=card"
title="Daily logic puzzle"
loading="lazy"
sandbox="allow-scripts allow-same-origin allow-popups"
referrerpolicy="strict-origin-when-cross-origin"
style="display:block;width:100%;max-width:540px;height:720px;border:0;background:transparent"
></iframe>