Implementation of achievement systems in modern, complex games

Question

Many games that are created these days come with their own achievement system that rewards players/users for accomplishing certain tasks. The badges system here on stackoverflow

Answer 1

You can even do this if you don't have access to source, for example in videogame emulators. A simple memory-scan tool can be written to find the displayed score for example. Once you have that your achievement system is as easy as polling that memory location every frame and seeing if their current "score" or whatever is higher than their highest score. The cool thing about videogame emulators is that memory locations are deterministic (no operating system).