Superb demo! I played through once with each of the characters, and the tutorial.
Duke of Bohemia
My goal was to create the kingdom, but I never reached 200 piety. Instead I fabricated some claims on fellow dukes of the HRE and stole their land for pastime. Ruler changed once, and as the inheritance law was based on seniority my brother took over. My son didn't like this and ended up in prison after a failed rebellion. After pissing off too many neighbouring dukes I though I was in trouble since they outnumbered me greatly. Luckily I was rich and employed some mercenaries to beat the fools back away. And as I was pushing for their territories the 20 year limit hit.
Matilda of Tuscany
I didn't set up any particular goal, but decided to some land-grabbing. Venice looked nice and after some fabricated claims and a brief war it was mine. Shortly after the duke of Lombardia decided I needed to lose some land and invaded. Too bad for him as while I defeated his armies my ever clever chancellor made up some propostorous claim for me to practise some land-grabbing on him. My armies counter-invaded, but after being 5 years in the game Matilda kicked the bucket for unknown reasons and left no heir, ending the game. What a bummer.
Duke of x, heir to Byzantine Empire
I inherited the empire so soon that I had no time even plot for it. Then I died too and my infant son took over. He (or his reagent) fought off multiple deposition/independence attempts and in the meantime took over sicily. Which was stupid. You don't want a land that rebels all the time and requires ships to reach. The grandson of the original emperor had a fun time invading infidels and whilst his time was filled with war it was kinda fun. But after some pagan bashing the time limit hit and it was time to move on. I was quite surprised that I managed to keep the byzantine vassals in check. I used chancellor on the most angry duke and gave titles to those who could be tipped over to liking me with it. And not even the turks seemed to want my stuff too badly. Compared to CK I Byzantine seems much more survivable.
King of Poland
DEUS VULT said the king and sent his men to invade the neighbouring pagans. Too bad that instead of accepting to taken out individually they grouped up and invaded poland after destroying it's armies. After despairing for some time the king hired mercenaries, enough to take out the pagans, but so expensive that they would soon ruin him. The mercenaries killed the savages and sieged their clumsy forts. As the treasury ran dry the pope saw fit to send massive amounts of gold to support the heathen hunt. 20 years later the king of poland had used mercenaries funded by the papal states to take over most of lithuania and what little they held of northern poland. As a fun side incursion his wife, Matilda of Tuscany had him involved in fighting the HRE for her independence. Just as the war was turned into their favor against the emperor, Matilda folded and accepted peace on lousy terms. Needless to say, the polish king found someone else to warm his bed. Between Matilda and his new bed-pal the king had many sons and daughters, but sadly all of the sons were murdered by his brother and after he died in the oubliette his son (king's nephew) took over the murder-the-heir-to-the-throne -business. After 20 years of busy breeding the king had no living male issue.
All in all good times. Didn't encounter any bugs or problems. Only thing that bummed me was with the pagan defend the faith thing: You declare war on pagan A (holy war), B and C pagans declare war on you (defend faith or whatever). Now you bash all three pagans, but you only get A's lands and are forced to truce the two other without getting their land. And while you beat their troops down, some jackass (danes) swoop in with their holy wars on B and C and take their lands for free. Or maybe I didn't get it right.
