Well if you are just against the modern, try Mount and Blade, and the standalone expansion, Warband.

Go with the original first, unless you are an oldergraphicsphobe.
They just released a new version of the original -
http://download.taleworlds.com/mountand ... hanced.exe - which removes, among adding other things, a nagging large party management issue. Requirements are pretty low, if you can run HD2 or even HDD, you can run this.
It takes places in a fictional, but historically based, European region, starting in 1257. The expansion updates textures and adds new weapons, some weapons 50 to 100 years before their time. No problem as you can easily mod this game, welcome to 1357.

Also a new faction and reintroducing a forced into, but can opt out of, storyline. As well as, of course, other things.