That's an interesting thread! I'm a big fan of games that try to simulate a world that doesn't revolve around me as the player.
Mount and Blade was one of the most astonishing experiences of this kind. Whole empires rise and fall, borders shift as a result of wars, there is an extreme amount of independent activities on the map and I as the player am merely one tiny individual trying to survive in this world.
In a very similar way Doomdark's Revenge fascinates me. This game from 1984 managed to create a world that lived by itself on 48kb. Similar to Mount and Blade, countless warlords of five different races roam the desolate plains of the Icemark with their troops, sit in their fortresses, wage wars one against another, completely without my involvement. Every single warlord has his own character traits, is part of a feudal order and acts accordingly. Nothing is scripted so the craziest stuff can happen. This game makes me dizzy everytime I remember it. Mike Singleton was a genius like no other.
Another rather obscure game with some similarity is PC Kaiser, a German shareware strategy game for MS-DOS from the early 90ies. The player finds himself as a noble in a feudal world and follows his "Wille zur Macht". There are a good dozen of competing aristocratic houses and they act completely independent, they arrange marriages, they inherit lands from deceased relatives, wage war against each other, annex land of their enemies, send assassins to murder each other. Revolutions happen, overthrowing whole kingdoms and giving birth to new countries... Nothing is scripted here too so every game will be different from the last. For a 100kb game there is an extreme amount of activity and life in this little game.
It may be a strange to bring an adventure game into this discussion, but I have to mention The Last Express. Everything is scripted in this game, sure, and follows a very rigid order, but this game managed to create the illusion of a living world for me like no other: As a passenger on board of the Orient Express, I feel exactly like that, because the other passengers follow their own activities, nobody is waiting for me. Because of the (pseudo-)realtime nature of the game it's entirely possible for me to miss important dialogues, because everything happens with or without my presence. There are some other adventures that use such a realtime approach as well (The Case of the Cautious Condor or Murder Makes strange Bedfellows come to my mind) but TLE was the most elaborated game of this kind.