Earlier quoted context omitted.
The developers frequently blog about how they're doing it, often going into immense detail. Without spoiling too much, I have no qualms about calling them some of the best in the industry. The entire industry, that is, not just in games.
Their blog posts are great. They sometimes blog about really obscure parts of game development. It’s interesting to read even if you are not building games.
...and here they are: https://factorio.com/blog/