One metaphor for The Sims I had while developing it was that it was like a pinball machine with lots of balls in play at once -- all the characters, bouncing around off of each other and the objects in the house, which can run autonomously without any user input, but then you can change the simulation's fate with the flippers (pie menus selecting actions overriding the default behavior).

But Factorio is like a pinball machine with MILLIONS of balls in play at the same time, and it perfectly and efficiently tracks each and every one of them.

There is one sad aspect to Factorio: There is only one character: you. Alone. On a planet. All by yourself. Destroying the environment. But once you get over that depressing aspect, it's great fun! ;)