@Nu_Fenix: I've been running a game vaguely along these lines for some years (of real time) now. The concept is historical fantasy set in Iron-Age Britain in the first century BC. It is a player-vs-player game using D&D 3.5 and the
Fields of Blood supplement (with rules for mass battles and, more importantly, realm management), with five petty warlords (all players) vying for supremacy over the shared tribal land while forces both within (street-gangs of sorcerer-bandits) and without (the Roman legions under Caesar just across the Channel in Gaul) threaten their very way of life. It's been a fairly slow-moving grind at times, but has continued to truck on, and we're about to enter our second winter.
As it happens, we seem to be, er, about to have an opening in the ranks. Despite the "lateness of the hour", there's no reason to be concerned about joining at this stage - there have been relatively few long-term territorial changes so far and you would be taking over an existing clan holding from a defeated warlord (to be clear, it is only the warlord himself, not the realm or its standing army, that have been defeated at this point), rather than struggling to build from scratch against much more well-established rivals.
Here's the link so you can take a bit of a closer look if this sounds at all appealing:
link to another game