What's the most unexpected source of traffic you've ever gotten?

I recently stumbled across a browser game called Linguaboard while researching language-learning projects.

https://www.machinetranslation.com/games/linguaboard

What surprised me wasn't the game itself, it was how much time I spent playing "just one more round."

As indie hackers, we often think in terms of features, growth loops, SEO, and monetization. But sometimes a simple game mechanic can be more engaging than an entire SaaS onboarding flow.

It got me wondering:

Have you ever borrowed an idea from a game and used it in your product?

What was it, and did it work?