Heir to the Throne is the third expansion to the historical strategy game Europa Universalis III.
The expansion takes the very successful game beyond complete, with improvements including an intriguing Casus Belli system, where wars have specific goals from start to finish, Monarchs now belong to dynasties, with far reaching effects on the diplomatic model. A More involving and powerful Holy Roman Empire and Papacy options and Special diplomatic options for Republics. Players are able to set your National Focus in a province to enhance growth and strengthen your hold in the region.
Permanent Terra Incognita has been removed and replaced with impassable regions as well as Cultural Tradition allows better advisors in the same way that Military Tradition allows better generals and admirals. Spheres of Influence simulate the Great Game of the major powers. There are more dynamic pirates. You can issue letters of marque to plague the sea zones of rival nations and Monarchs need to uphold their legitimacy in the eyes of their subjects.