Oh dude,
Warband is fucking amazing for getting lost in a game like that. It's hard to explain but you start out as a peasant (or a bannered nobleman, if you wanna make it easy) and run around a huge map recruiting/upgrading soldiers from villages while you build relationships with the various Kingdoms until they offer you a fiefdom/vassalage or you get bold and start your own kingdom (not recommended for your first time.)
It's also from like at least 2012, maybe further back than that, so your computer should handle it perfectly. It's a hell of an immersive game, but the graphics leave a lot to be desired. Really the only time the graphics bother me is when I'm in-battle or roaming around a village or a town, but the battles are so fun and the graphics passable enough for me to just not even care about it. Like, all the possible tactical formations and strategies and randomly created maps for the battles lead to endless possibilities. Check out a video if you wanna know what I mean, but keep in mind the beginning is just homie setting up his troops in an advantageous position (though he fucked up, because his archers should've been about 50 paces forward on top of the hill instead of at the base to catch the enemy charge) while the enemy either does the same or blindly charges depending on how well that particular AI knows or feels about you:
https://www.youtube.com/watch?v=IwAvZTOVSsw
But there's a new Mount and Blade about to come out,
Mount and Blade: Bannerlord, so the prices are probably dropping or about to drop
drastically for
Warband.