Dark Souls. It's renowned for being difficult, and it is, but it feels great learning the ropes and eventually becoming pretty good. And then you can do it all over again with different weapons, armor, covenants, etc. on a new character, or you can try New Game+.
If you do play it (on PC), I recommend a controller but some people say DSMfix makes it playable with keyboard and mouse. You'll want DSfix and you should take a look around the Dark Souls Nexus for other mods that interest you. --- Steam: Sydite
Divinty: Original Sin is in pre-alpha testing right now. Still has lots of hours that you can play, expect lots of bugs though. The game is story driven and it's in pre-alpha so it's not all there. Might be a no because of that. Though it's still really fun to play. --- Hard work pays off in the future. Laziness pays off now.
Mount and Blade: Warband. One of the greatest games ever created, period. --- It is a capital mistake to theorize before one has data. ...one begins to twist facts to suit theories.... Sir Arthur Conan Doyle