Each player steers the leader of one of the countries in medieval europe and tries to enlargen his territory and conquer the heretics in the east.
The game consists of two main parts:
1. Leading your country
2. Leading your family
While the first part is quite similar to other titles of Paradox (Hearts of Iron, Victoria and Europa Universalis series) the second part is unique.
You control the head of the family and therefore chose who marries who and how your children and grand-children are to be raised. This may lead to stronger siblings or evil kids who should be kept from the throne.