Last weekend I started playing Crusader Kings gain, but then I stopped because the game was pissing me off too much. The reason why I dig Paradox games is because they simulate geopolitics in a manner that is fairly accurate, yet nonetheless simple and intuitive. However, while CK nails the political side of things very well (dynasty mechanics are well-designed and, to the best of my knowledge, unique in the grand strategy genre), the whole "geo"-aspect is overly simplified and permits absurdly unrealistic situations and scenarios.
For instance, independent counts and princes are very keen to accept vassalization offers from kingdoms of the same religion. However, this is a problem for Slavic lands in Eastern Europe, because there are no Orthodox Christian kingdoms there. As a result, local princes and counts usually end up accepting vassalization offers from kings of Georgia and Serbia, which is absurd, as both Georgia and Serbia are quite a distance away and have no way of projecting their power as far as, say, Suzdal or Novgorod. So now Georgia and Serbia together rule pretty much the entire Eastern Europe (territory about, oh, ten times their size). To make things even more ridiculous, some pissant Irish dynasty took control of Hungary at some point (I have no idea how it happened, one minute Bela III was still king of Hungary, next Bela III is dead and his throne is occupied by some dude name Conchobar) and by some strange successional twists the current king of Connacht inherited several counties in eastern Hungary, so now I have fucking Ireland expanding into south-eastern Europe.
Anyway, right now I'm looking for mods that improve the game's geopolitical model, but so far I have had no luck. Seems CK is quite obscure compared to more popular Paradox games like EU and HoI. Damn shame, as it really has loads of potential.