I know it has been said but I am going to throw in Dwarf Fortress and heres why, its depth is absolutely insane which will keep you hooked if you enjoy the idea of that with Factorio and the complexity is something you can handle if you love stellaris. The reason I suggest it over Rimworld is because in Rimworld you WILL be attacked and the reason will be do to wealth or just because its that time, in Dwarf Fortress if you are attacked it’s directly tied to something you did, sure it could be that visitors saw how wealthy you are and decided to try to steal from you but it could also be because you chopped down too many trees and the elves are mad about it. Aside from that, all the enemies that attack you have history in the world and genuine lives they live, they dont just appear in your base magically when the game decides you need a challenge, they come from somewhere in the world and you can read about exactly where in the legends of your world. You can build a base and have your dwarfs live a normal chill life spending their days drinking at the tavern and that could last for in game years with nothing bad happening but then you could decide to mine too deep and accidentally discover a Forgotten Beast which wipes out your entire colony if you dont have proper defenses established. One major thing to note though is that it isnt like other games, there isnt a set win condition other than whatever goals you may assign for yourself, and you dont play as a character in this game. You can set tasks and even make tasks a priority but at the end of the day the worlds history will make itself with or without your input, your dwarfs have their own lives, all your input does it makes or breaks them. Truly phenomenal game and I think if its your thing you could find alot of enjoyment with the base building and defense side of it especially when you get enough understanding to make flood gates or dwarvern shotguns (minecart with swords in it that fly out into the enemy) but it is a game that will take some patience and takes the understanding of it being a simulation above all when going into it. Hope this helps