This is my ultimate challenge for myself and for other people as well.

It is very simple, and for me extremely hard to do which is why I like playing this way.

Be the ultimate chivalric line as a catholic nation, no matter who attacks you do nothing but defend your land (do not send your lads into another catholic faction's lands) even when they take two of your princessess and then attack you breaking the alliance, do not declare war on anyone else instead wait for them to attack you, and even then only destroying the armies that invade your lands join every Crusade that is called with a majority of your soldiery while leaving only a skeleton force at home for defence, regulary give money to the Papacy just out of the goodness of your heart, in Europe only take rebel provinces which historically belonged to your faction, and if that doesn't increase the excitement enough while on Crusades or retaking towns in your homeland you occassionally lose never press the exterminate button that is for knaves and primitive impalers not chivalric royalty you must on top of everything else accept having to have high squalor and high unrest cities. You do not start trying to take over the map untill some time in the 15th century which is when you may also stop giving regular gifts to the now exposed as frauds Papacy, which is balanced because at this point you may face pretty good enemy technology.

Has anyone else tried my special challenge?

P.S I find that diplomacy is actually useful in this mode for getting the evil agressors who take advantage of my absence on Crusades, and at the same time it helps my Crusader Armies because they are made up of the vast majority of my forces, and the best to, although the obvious disadvantages of having ever growing in power nemies.