Crusader Kings II achievements

Go on a Christian Pilgrimage

Build an Observatory

Successfully establish a trade route

Assassinate a vassal bishop that likes the Pope better than you

Win a war using Mercenaries.

Build a Hospital.

Fulfill the goal of a Crusade

Successfully intervene in a youth's development to force one of your own traits onto them.

Go into Seclusion.

Work your way up from Count to Duke with a single character

Contract three symptoms.

Have your spouse assassinated