I created Every 5x5 Nonogram, a web game where thousands of internet strangers collaborated to solve all ~25 million well-formed nonogram puzzles, about five months ago. Hundreds of thousands visited and it was briefly featured on Hacker News (
https://news.ycombinator.com/item?id=44140918). I created part 1 of a technical behind-the-scenes covering the idea, architecture, and launch. It's on my patreon, but its free for all to view, if interested.