Crusader Kings II is a strategy game set in the Middle Ages where players control a medieval dynasty.
Pro Freedom to play how you like
The game allows for one to make their own choices with there being many "win" conditions in that you can choose to progress how you like. Want to take over all of Europe, that is possible, want to create a successful lineage of family that keeps to themselves, this is also possible.
Con Extremely complicated
Crusader King II is a very complicated game that seems overly complex at first and may take a while to really learn as there are quite a lot of things to not only balance in the game but also figure out how to do either through in game tutorials or reading online.