For a large Dutch publisher, I built the backend API for one of their new interactive games. Within weeks after launching, the game grew to over 60.000 users, while keeping response times on the API below 30 ms, by using smart caching and the right choice of data store to keep user scores. At peak times over 600 requests a second were handled by this custom backend, which run on only 3 servers. Calculating daily scores and winning users, a process that used to take over an hour, was optimized to run in a few minutes.
The backend was build on PHP, CodeIgniter, Nginx, Redis and MySQL.