Played as Castile. Despite having five sons, they all died from illness or treachery(damn Leonian king assassinated my heir so he could inherit my kingdom!). Finally, I had 1 daughter, Corexia, who managed to survive until she was 16. I had a pretty fun game then, trying to manage my few vassal's due to their negative opinion of me. Fortunately, I had successful holy wars against the muslims and managed to gain lots of land. Even managed to snatch the Duchy of Aragon from my cousin. Everything fell apart when I appointed my future husband to the Duchy of Aragon and granted him a few counties. I forgot that you had to do a matrilineal marriage to allow a women to have the children. Instead, all the son's were of my husband's family instead of mine. So when Corexia died, I lost since I had not family to inherit my kingdom. All in all a pretty fun game.