The verb, not the noun.
I've found that a common thread through many of my favorite games is the ability to build up some sort of empire during the game. The Suikoden series games all have this, to lesser or greater degrees. GTA Vice City, Vice City Stories, and Scarface even refer to that part of the game as empire building in-game, iirc. Saint's Row 2 (and I assume 3) has a similar implementation. I was kind of surprised when I found out that the development of MSF into a private army was a big part of MGS: Peace Walker, and I've put over 100 hours into that game so far.
One game I had hoped would include this was the kind of old PC game Republic, but I picked it up and just couldn't get into it. Fable 1 didn't exactly have this, but it did allow you to kill almost every person in Albion, buy their vacant houses, and then charge exorbitant rent to the immigrants who replace them.
Did you ever try out The Godfather: The Game?
I have not! I'm pretty wary of any EA game released after Nuclear Strike. Aside from Dead Space and Burnout: Dominator I haven't played an EA developed game I've liked that's come out in the past 18 years.
It was a pretty un-egregious GTA3 clone. I enjoyed playing it through to the end.
This was one of my favorite parts of San Andreas and then I inadvertently triggered some sort of plot development which exiled me from my own hood.
Try Mount&Blade:Warband. You start as a lone mercenary, but will quickly swear allegiance to some faction and could later rebel and start your own kingdom. You can also try to start your kingdom from scratch but that will sic the entire world on your ass.
What I find charming about Warband is that every noble is an autonomous actor and will switch lords to improve their position. They have their own army, their own goals and move on their own expanding or protecting their land. The allows you to lure enemy or friendly lords to your kingdom or knight your own followers and make them vassals (with all the advantages and disadvantages of real lords).
The game is far from perfect, though - it's world is rather empty and there are few quest that are actually worth doing. But it still has the best horseback fighting I know of.