Many video games, especially PC based ones, allow you to modify them. You usually are given a restricted API to work with, allowing you to manipulate the game in specific ways. Normally, you can’t really break the game per se, but you can indeed mess up with mods. But when you make a killer mod, people worldwide can benefit from it. I found a niche issue in Elder Scrolls Online, which I am writing a mod for.
This article is just a discussion about how I go about learning what I need to make a mod, as well as some info on the mod I’m working on.